A review on the progress of nanostructure materials for energy harnessing and environmental remediation
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paper_title: Nanostructured materials: basic concepts and microstructure☆

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Abstract Nanostructured Materials (NsM) are materials with a microstructure the characteristic length scale of which is on the order of a few (typically 1–10) nanometers. NsM may be in or far away from thermodynamic equilibrium. NsM synthesized by supramolecular chemistry are examples of NsM in thermodynamic equilibrium. NsM consisting of nanometer-sized crystallites (e.g. of Au or NaCl) with different crystallographic orientations and/or chemical compositions are far away from thermodynamic equilibrium. The properties of NsM deviate from those of single crystals (or coarse-grained polycrystals) and/or glasses with the same average chemical composition. This deviation results from the reduced size and/or dimensionality of the nanometer-sized crystallites as well as from the numerous interfaces between adjacent crystallites. An attempt is made to summarize the basic physical concepts and the microstructural features of equilibrium and non-equilibrium NsM.
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paper_title: State-of-the-Art Progress in Diverse Heterostructured Photocatalysts toward Promoting Photocatalytic Performance

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Semiconductor photocatalysts have received much attention in recent years due to their great potentials for the development of renewable energy technologies, as well as for environmental protection and remediation. The effective harvesting of solar energy and suppression of charge carrier recombination are two key aspects in photocatalysis. The formation of heterostructured photocatalysts is a promising strategy to improve photocatalytic activity, which is superior to that of their single component photocatalysts. This Feature Article concisely summarizes and highlights the state-of-the-art progress of semiconductor/semiconductor heterostructured photocatalysts with diverse models, including type-I and type-II heterojunctions, Z-scheme system, p–n heterojunctions, and homojunction band alignments, which were explored for effective improvement of photocatalytic activity through increase of the visible-light absorption, promotion of separation, and transportation of the photoinduced charge carries, and enhancement of the photocatalytic stability.
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paper_title: Continuous-mode photocatalytic degradation of chlorinated phenols and pesticides in water using a bench-scale TiO2 rotating disk reactor

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Abstract Photocatalytic degradation of phenol, chlorinated phenols, and lindane was evaluated in a continuous flow TiO2 rotating disk photocatalytic reactor (RDPR). The RDPR operated at a hydraulic residence time of 0.25 day and at a disk angular velocity of 12 rpm. At low molar feed concentrations (0.038 mmol/l), the removal efficiencies for phenol and chlorinated phenols were in the order of 86% or higher, whereas the removal efficiency for lindane at a feed concentration of 0.016 mmol/l was in the order of 63%. For 2,4,6-trichlorophenol (TCP), an increase in the molar influent concentration resulted in a decrease in removal efficiency but in an increase in removal rate. The degradation rate of 2,4,6-TCP followed a saturation type dependancy with the effluent concentration, suggesting a Langmuir–Hinshelwood (L–H) reaction rate equation. A L–H equation was employed to determine the reaction rate constant and the adsorption coefficient for 2,4,6-TCP. The photonic efficiency increased from 0.68% at an influent concentration of 0.13 mmol/l to 2.06% at an influent concentration of 1.0 mmol/l.
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paper_title: Mechanical properties of nanoparticles: basics and applications

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The special mechanical properties of nanoparticles allow for novel applications in many fields, e.g., surface engineering, tribology and nanomanufacturing/nanofabrication. In this review, the basic physics of the relevant interfacial forces to nanoparticles and the main measuring techniques are briefly introduced first. Then, the theories and important results of the mechanical properties between nanoparticles or the nanoparticles acting on a surface, e.g., hardness, elastic modulus, adhesion and friction, as well as movement laws are surveyed. Afterwards, several of the main applications of nanoparticles as a result of their special mechanical properties, including lubricant additives, nanoparticles in nanomanufacturing and nanoparticle reinforced composite coating, are introduced. A brief summary and the future outlook are also given in the final part. (Some figures may appear in colour only in the online journal)
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paper_title: Synthesis of CuO-ZnO nanophotocatalyst for visible light assisted degradation of a textile dye in aqueous solution

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An attempt was made to prepare CuO/ZnO nanophotocatalyst for visible light assisted degradation of a textile dye (Acid Red 88) in aqueous solutions by wet impregnation method. The CuO/ZnO samples annealed at 550 °C for 5 h were changed from purple to grey, indicating that CuO clusters on ZnO may not be metallic Cu but it may be CuO-ZnO. Characterization using Transmission Electron Microscopy (TEM), Diffuse Reflectance Spectroscopy (DRS), X-Ray Photo Electron Spectroscopy (XPS) and X-Ray Diffraction (XRD) analysis confirms that only CuO phase is present in the as prepared sample. The prepared CuO-ZnO shows approximately 2 times more photocatalytic activity compared to that of bare ZnO and as well as enhanced photocatalytic activity in the presence of external electron acceptors such as PMS (peroxomonosulphate), PDS (peroxodisulfate), and H2O2 (hydrogen peroxide). Total organic carbon (TOC) experiments also support such enhanced activity.
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paper_title: Z-Scheme Water Splitting Using Two Different Semiconductor Photocatalysts

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Water splitting on illuminated semiconductors has long been studied as a potential means of converting solar energy into chemical energy in the form of H2, a clean and renewable energy carrier. Photocatalytic water splitting through two-step photoexcitation using two different semiconductor powders and a reversible donor/acceptor pair (so-called shuttle redox mediator) is one of the possible forms of artificial photosynthesis. This system was inspired by natural photosynthesis in green plants and is called the “Z-scheme”. The development of Z-scheme water splitting systems has relied on both finding a new semiconductor photocatalyst that efficiently works in the presence of a shuttle redox mediator and creating active sites to promote surface chemical reactions while suppressing backward reactions involving redox mediators. This review article describes the historical development of photocatalytic water splitting systems driven by the Z-scheme principle.
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paper_title: Photocatalysis A to Z : What we know and what we do not know in a scientific sense

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Abstract Topics, in alphabetical order from “Activity”, “Band structure” and “Crystallinity” to “X-ray photoelectron spectroscopy”, “Yield” and “Z-scheme photocatalysis”, related to photocatalysis and photoelectrochemical reaction are discussed with interpretation of what we know and what we do not know in a scientific sense.
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paper_title: A review on recent advances in photodegradation of dyes using doped and heterojunction based semiconductor metal sulfide nanostructures for environmental protection

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Abstract Among the admired photocatalysts, metal sulphide-based semiconductors are most prominent photocatalysts for the degradation or decomposition of dyes in wastewater industries with low cost, environment-friendly and sustainable treatment technologies for the environmental protection. In recent years, the environmental pollution poses a serious threat to the environment and public health. To overcome the environmental pollution, doped and heterojunction based semiconductor metal sulfide nanostructures (MSNSs) are developed as photocatalysts for the purpose of photocatalytic degradation or removal of large organic dyes in an eco-friendly and sustainable fashion. This comprehensive review starts with a brief overview on dyes as pollutants, dyes classification, dyes decolorization or degradation strategies and focuses on the mechanisms involved in comparatively well understood MSNSs photocatalysts such as ZnS, CdS, CuS, Ag 2 S, Bi 2 S 3 , CoS, FeS, and PbS etc. It particularly discusses the recent advancements to enhance photocatalytic degradation of toxic dyes by using various MSNSs to make it a flexible and cost-effective commercial dye treatment technology. In addition, we have focused on the treatment of organic dyes using different types of MSNSs by photocatalysis and the effects of various parameters such as dopants, heterojunctions, band gap, size, light intensity, surface area, reaction time, and degradation efficiency, etc., are highlighted.
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paper_title: Materials science: Nanomaterial advantage

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Materials may be strong or ductile, but rarely both at once. The processing of copper into a nanostructure possessing different-sized grains produces a material that retains its high strength and ductility under deformation.
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paper_title: In-situ synthesis of visible-light responsive Ag2O/graphene oxide nanocomposites and effect of graphene oxide content on its photocatalytic activity

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Ag2O/graphene oxide nanocomposites, as efficient photocatalysts, were prepared by an in situ method using AgNO3 and graphene oxide as reactants under controlled atmosphere. Graphene oxide is synthesised via an eco-friendly method, and the Ag2O nanoparticles displaying elongated spherical morphology are randomly distributed on the surface of GO. The as-synthesised nanocomposites were characterised by different characterisation techniques. The results proved that the concentration of graphene oxide in starting solution displayed an important role in photocatalytic performance of Ag2O/graphene oxide nanocomposites. The nanocomposite materials were found to exhibit very improved photocatalytic activity for degrading methylene blue (MB) and Rhodamine B (Rh-B) under visible light irradiation. The photocatalytic activities of the composite were higher than that of P25 (a commercial TiO2 as a benchmark photocatalyst). The significantly improved photocatalytic activity of the nanocomposites could be attributed to the high charge separation and suppressed recombination of photogenerated electron-hole pairs due to GO. The effects of reaction parameters such as pH and the effect of different scavengers on the photocatalytic activity of the composite were studied.
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paper_title: A feasibility study on photocatalytic degradation of methyl benzene using N doped TiO2 nanoparticles

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Volatile organic compounds (VOCs) are common hazardous pollutants found in air, water and soil. In the present study, laboratory designed batch and continuous photocatalytic degradation of methyl benzene, a major contaminant in water, is demonstrated using N doped TiO2 photocatalyst. The N doped TiO2 photocatalyst was prepared under the sol-gel techniques and characterised by different analytic techniques. Treatment efficiency of N doped TiO2 photocatalyst was carried out under the visible-radiation source using laboratory scale reactors such as batch reactor, fluidised moving bed reactor and packed column bed reactor. The effects of parameters viz., photocatalyst concentration, recovery and reusability of the photocatalyst on degradation of VOCs were studied. Simulated methyl benzene in water showed maximum degradation efficiency of 74% in fluidised moving bed reactor; in the packed bed continuous reactor and batch reactor the values were 40% and 50%, respectively.
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paper_title: Hydrothermal Synthesis and High Photocatalytic Activity of 3D Wurtzite ZnSe Hierarchical Nanostructures

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Novel 3D wurtzite ZnSe hierarchical nanostructures have been synthesized by a mild hydrothermal treatment. The as-prepared flowerlike nanostructures efficiently catalyze the photodegradation of methylene blue and ethyl violet present in aqueous solutions under UV light irradiation, exhibiting higher photocatalytic activity than the commercially available photocatalysts P25 and ZnSe microspheres. We also demonstrate that flowerlike morphology is important for the excellent photocatalytic activity. The high photoactivity of the hierarchical nanoflowers can be attributed to the combined effects of several factors, namely, large surface areas, the existence of mesopores, and the high band gap energy. In addition, the photocatalysts work effectively under natural sunlight as well. To the best of our knowledge, this is the first time that wurtzite ZnSe 3D flowerlike nanostructures with high photocatalytic activity have been synthesized in solution.
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paper_title: A TaON nano-photocatalyst with low surface reduction defects for effective mineralization of chlorophenols under visible light irradiation

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TaON nanoparticles with low surface reduction defect sites were successfully constructed by a simple nitridation approach using Ta2O5·nH2O as a precursor. Large amounts of crystal water in Ta2O5·nH2O are considered as a parclose to prohibit Ta5+ from being reduced in the nitridation process with NH3 gas. Urea was also used in the synthesis, acting as a co-nitridation agent together with NH3 but also as a porogen for creating nanopores in TaON frameworks. The as-prepared TaON catalyst was evaluated by environmental purification of organic pollutants in water, as exemplified here by mineralization of phenol and its chloroderivatives in aqueous phase under visible light irradiation. Results revealed that a lower defect density of TaON, as well as its nanopore structure and smaller particle size, contribute to the promotion in both electron–hole separation and interfacial charge-transfer in materials surface/interface, being the main reasons for the enhanced photocatalytic performance.
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paper_title: State-of-the-Art Progress in Diverse Heterostructured Photocatalysts toward Promoting Photocatalytic Performance

paper_content:

Semiconductor photocatalysts have received much attention in recent years due to their great potentials for the development of renewable energy technologies, as well as for environmental protection and remediation. The effective harvesting of solar energy and suppression of charge carrier recombination are two key aspects in photocatalysis. The formation of heterostructured photocatalysts is a promising strategy to improve photocatalytic activity, which is superior to that of their single component photocatalysts. This Feature Article concisely summarizes and highlights the state-of-the-art progress of semiconductor/semiconductor heterostructured photocatalysts with diverse models, including type-I and type-II heterojunctions, Z-scheme system, p–n heterojunctions, and homojunction band alignments, which were explored for effective improvement of photocatalytic activity through increase of the visible-light absorption, promotion of separation, and transportation of the photoinduced charge carries, and enhancement of the photocatalytic stability.
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paper_title: High Stability and Efficiency of GaN Photocatalyst for Hydrogen Generation from Water

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Continuous hydrogen generation from water was realized for 110 h using an n-type GaN film with a NiO cocatalyst. This GaN–NiO photocatalyst exhibits incident photon-to-current conversion efficiencies of 70 and 57% at wavelengths of 300 and 350 nm, respectively. These results indicate that the GaN–NiO photocatalyst has high stability and efficiency for hydrogen generation.
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paper_title: Ecofriendly Synthesis and Photocatalytic Activity of Uniform Cubic Ag@AgCl Plasmonic Photocatalyst

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Uniform cubic Ag@AgCl plasmonic photocatalyst was synthesized by a facile green route in the absence of organic solvent, in which a controllable double-jet precipitation technique was employed to fabricate homogeneous cubic AgCl grains and a photoreduction process was used to produce Ag nanoparticles (NPs) on the surface of AgCl. During the double-jet precipitation process, the presence of gelatin and Cl– ions at low concentration was necessary for the formation of cubic AgCl grains. Atomic force microscopy (AFM) was used to probe the morphological structure of Ag@AgCl grains for the first time, which showed that Ag NPs are anchored on the surface of AgCl grains like up-and-down mounds. Further characterization of the photocatalyst was also done by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–visible diffuse reflectance spectroscopy (DRS). The as-prepared Ag@AgCl plasmonic photocatalyst exhibited excellent photocatalytic efficiency for the deg...
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paper_title: An oxynitride, TaON, as an efficient water oxidation photocatalyst under visible light irradiation (λ≤ 500 nm)

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Under visible light irradiation (λ ::: = 420–500 nm), a tantalum oxynitride, TaON, functions as a stable and very efficient photocatalyst for oxidation of water into O2 with a sacrificial electron acceptor (Ag+).
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paper_title: Z-Scheme Water Splitting Using Two Different Semiconductor Photocatalysts

paper_content:

Water splitting on illuminated semiconductors has long been studied as a potential means of converting solar energy into chemical energy in the form of H2, a clean and renewable energy carrier. Photocatalytic water splitting through two-step photoexcitation using two different semiconductor powders and a reversible donor/acceptor pair (so-called shuttle redox mediator) is one of the possible forms of artificial photosynthesis. This system was inspired by natural photosynthesis in green plants and is called the “Z-scheme”. The development of Z-scheme water splitting systems has relied on both finding a new semiconductor photocatalyst that efficiently works in the presence of a shuttle redox mediator and creating active sites to promote surface chemical reactions while suppressing backward reactions involving redox mediators. This review article describes the historical development of photocatalytic water splitting systems driven by the Z-scheme principle.
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paper_title: Highly Stable GaN Photocatalyst for Producing H2 Gas from Water

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Efficient production of H2 from water without the use of an extra bias or any sacrificial reagents is possible using a GaN photocatalyst with a NiO cocatalyst. The average energy conversion efficiency from light energy to H2 energy was approximately 1% for 500 h. The total amount of hydrogen was 184 mL/cm2 of the GaN surface. H2 production rate was as high as 0.37 mL/(cm2h).
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paper_title: Solution processing of CuSe quantum dots: Photocatalytic activity under RhB for UV and visible-light solar irradiation

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Exploit of photodegradation and photocatalytic activity of large scale synthesis of (CuSe) copper selenide semiconductor quantum dots was reported. The obtained nanocrystals were characterized by X-ray diffraction (XRD), UV-visible absorption spectroscopy (UV-vis) photoluminescence (PL) and high resolution transmission electron microscopy (HRTEM). The crystalline, nearly monodisperse with uniform size were synthesized by the reflux condensation method. This method promises a range of possibilities for the preparation of CuSe materials with enhanced properties. Experimental investigation shows the nanoscale photocatalysts with high surface area, small particle size and high crystallinity is of current interest in nanophase materials. The chemical composition of the CuSe samples and the valence states of elements were determined by X-ray photoelectron spectroscopy (XPS). We present our investigations to the shape and size of the quantum dots and are good agreement with experimental results.
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paper_title: A Review on Visible Light Active Perovskite-Based Photocatalysts

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Perovskite-based photocatalysts are of significant interest in the field of photocatalysis. To date, several perovskite material systems have been developed and their applications in visible light photocatalysis studied. This article provides a review of the visible light (λ > 400 nm) active perovskite-based photocatalyst systems. The materials systems are classified by the B site cations and their crystal structure, optical properties, electronic structure, and photocatalytic performance are reviewed in detail. Titanates, tantalates, niobates, vanadates, and ferrites form important photocatalysts which show promise in visible light-driven photoreactions. Along with simple perovskite (ABO3) structures, development of double/complex perovskites that are active under visible light is also reviewed. Various strategies employed for enhancing the photocatalytic performance have been discussed, emphasizing the specific advantages and challenges offered by perovskite-based photocatalysts. This review provides a broad overview of the perovskite photocatalysts, summarizing the current state of the work and offering useful insights for their future development.
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paper_title: New Non-Oxide Photocatalysts Designed for Overall Water Splitting under Visible Light

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Overall water splitting to form hydrogen and oxygen over a heterogeneous photocatalyst using solar energy is a promising process for clean and recyclable hydrogen production in large-scale. In recent years, numerous attempts have been made for the development of photocatalysts that work under visible-light irradiation to efficiently utilize solar energy. This article presents recent research progress in the development of visible-light-driven photocatalysts, focusing on the refinement of non-oxide-type photocatalysts such as (oxy)nitrides and oxysulfides.
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paper_title: Facile Subsequently Light-Induced Route to Highly Efficient and Stable Sunlight-Driven Ag−AgBr Plasmonic Photocatalyst

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In this paper, we successfully fabricate a stable and highly efficient direct sunlight plasmonic photocatalyst Ag−AgBr through a facile hydrothermal and subsequently sunlight-induced route. The diffuse reflectance spectra of Ag−AgBr indicate strong absorption in both UV and visible light region. The obtained photocatalyst shows excellent sunlight-driven photocatalytic performance. It can decompose organic dye within several minutes under direct sunlight irradiation and maintain a high level even though used five times. In addition, both the scanning electron microscopy images and X-ray photoelectron spectroscopy dates reveal the as-prepared photocatalyst to be very stable. Moreover, the mechanism suggests that the high photocatalytic activity and excellent stability result from the super sensitivity of AgBr to light, the surface plasmon resonance of Ag nanoparticles in the region of visible light, and the complexation between Ag+ and nitrogen atom. Thus, the facile preparation and super performance of Ag−...
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paper_title: Enhancement in photocatalytic degradation of methylene blue by LaFeO3-GO integrated photocatalyst-adsorbents under visible light irradiation

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Perovskite LaFeO3 photocatalyst prepared by using sol-gel glucose method was assembled on graphene oxide sheets to produce integrated photocatalyst-adsorbents (IPCA) and investigated as photocatalyst for the degradation of methylene blue under visible light irradiation. The prepared photocatalyst was characterized by FTIR, XRD, FESEM, BET specific surface area measurement, TEM/HRTEM and UV-Vis spectroscopy analysis. The FTIR, FESEM and TEM analysis has suggested that the photocatalyst LaFeO3 has been successfully embedded at the surface of the graphene oxide (GO) sheets due to a strong interaction between the photocatalyst and the adsorbents matrix. Methylene blue degradation shows that IPCA possesses higher photodegradation kinetics compared to bare LaFeO3 photocatalyst. The resultant photocatalyst also possesses magnetic properties which can overcome the difficulty in recollecting and removal of photocatalyst suspension in water after photocatalytic treatment.
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paper_title: Ion-exchange synthesis and enhanced visible-light photocatalytic activities of CuSe-ZnSe flower-like nanocomposites

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Abstract CuSe-ZnSe flower-like nanocomposites with uniform diameters can be easily fabricated on a large scale by a controlled ion-exchange reaction between monodisperse ZnSe flower-like nanostructures and Cu2+ ions in solution. The difference of solubility products (Ksp) of ZnSe and CuSe is the main driving force for the formation of these flower-like nanocomposites. The Cu content greatly influences the physical properties and photocatalytic activity of obtained CuSe-ZnSe nanocomposites. The as-produced CuSe-ZnSe nanocomposites show tremendous enhancements on the photocatalytic degradation ratio of organic dyes methylene orange (MO) and methylene blue (MB) under visible-light irradiation. The 8 wt.% CuSe-ZnSe sample exhibits the highest degradation ratio for both MO (ca. 100%, 90 min) and MB (ca. 96%, 60 min), which are over 4 times and 2.5 times than that of the pure ZnSe sample, respectively. Based on the data of UV–vis diffuse reflection spectra, XPS and PL spectra, the enhancements of photocatalytic activities of CuSe-ZnSe flower-like nanocomposites are due to the effective separation of photo-electrons and holes induces by the direct initiates interfacial charge transfer (IFCT) from the valence band (VB) of ZnSe to CuSe, which results in the reduction of CuSe to Cu2Se. This work not only highlights the potential use of visible-light-driven CuSe-ZnSe flower-like nanocomposites photocatalysts, but also emphasizes the simple ion-exchange in situ growth method for the preparation of selenides heterogeneous structures.
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paper_title: The Functions of Fullerenes in Hybrid Perovskite Solar Cells

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There is increasing interest in the application of fullerene-based carbon materials in perovskite solar cells for increased efficiency, reduced hysteresis, and improved stability. This Perspective summarizes the progress in the understanding of the function of fullerenes in perovskite solar cells in blocking leakage through pin-holes, passivating the defects at the perovskite film surfaces and grain boundaries, and modulating the open-circuit voltage of the devices. We also critically reviewed several open questions on the functions of fullerenes in perovskite solar cells based mainly on recent progress: How do fullerenes reduce current hysteresis? What is the function of double-fullerene layers? Does the doping of the fullerene by perovskite contribute to eliminating the photocurrent hysteresis at room temperature? Why do some perovskite/fullerene solar cells still have hysteresis at low temperature? Are perovskite solar cells with fullerenes in the intergranular boundaries bulk heterojunction solar cell...
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paper_title: Material and energy intensity of fullerene production.

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Fullerenes are increasingly being used in medical, environmental, and electronic applications due to their unique structural and electronic properties. However, the energy and environmental impacts associated with their commercial-scale production have not yet been fully investigated. In this work, the life cycle embodied energy of C(60) and C(70) fullerenes has been quantified from cradle-to-gate, including the relative contributions from synthesis, separation, purification, and functionalization processes, representing a more comprehensive scope than used in previous fullerene life cycle studies. Comparison of two prevalent production methods (plasma and pyrolysis) has shown that pyrolysis of 1,4-tetrahydronaphthalene emerges as the method with the lowest embodied energy (12.7 GJ/kg of C(60)). In comparison, plasma methods require a large amount of electricity, resulting in a factor of 7-10× higher embodied energy in the fullerene product. In many practical applications, fullerenes are required at a purity >98% by weight, which necessitates multiple purification steps and increases embodied energy by at least a factor of 5, depending on the desired purity. For applications such as organic solar cells, the purified fullerenes need to be chemically modified to [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM), thus increasing the embodied energy to 64.7 GJ/kg C(60)-PCBM for the specified pyrolysis, purification, and functionalization conditions. Such synthesis and processing effects are even more significant for the embodied energy of larger fullerenes, such as C(70), which are produced in smaller quantities and are more difficult to purify. Overall, the inventory analysis shows that the embodied energy of all fullerenes are an order of magnitude higher than most bulk chemicals, and, therefore, traditional cutoff rules by weight during life cycle assessment of fullerene-based products should be avoided.
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paper_title: Photocatalytic degradation of organic dyes and enhanced mechanical properties of PAN/CNTs composite nanofibers

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Abstract This work describes the enhanced mechanical properties of the composite nanofibers and the photodegradation of two organic dyes using PAN/CNTs under UV irradiation at different volume concentration (0.05, 0.1, 0.2, and 0.3 wt.%). The composite nanofibers was performed with polyacrylonitrile (PAN), and carbon nanotubes (CNTs) by electrospinning process. The composite nanofibers structure and morphology is characterized by XRD, FTIR, SEM, and TEM. The result indicates that with increasing CNTs content, the mechanical properties of the composite nanofibers was enhanced, and became more elastic, and the elastic modulus increased drastically. The results of mechanical properties exhibit improvements in tensile strengths, and elastic modulus by 38% and 84% respectively, at only 0.05 wt.% CNTs. Moreover, photocatalytic degradation performance in short time and low power intensity was achieved comparison to earlier reports.
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paper_title: TiO2−Graphene Nanocomposites for Gas-Phase Photocatalytic Degradation of Volatile Aromatic Pollutant: Is TiO2−Graphene Truly Different from Other TiO2−Carbon Composite Materials?

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The nanocomposites of TiO2−graphene (TiO2−GR) have been prepared via a facile hydrothermal reaction of graphene oxide and TiO2 in an ethanol−water solvent. We show that such a TiO2−GR nanocomposite exhibits much higher photocatalytic activity and stability than bare TiO2 toward the gas-phase degradation of benzene, a volatile aromatic pollutant in air. By investigating the effect of different addition ratios of graphene on the photocatalytic activity of TiO2−GR systematically, we find that the higher weight ratio in TiO2−GR will decrease the photocatalytic activity. Analogous phenomenon is also observed for the liquid-phase degradation of dyes over TiO2−GR. In addition, the key features for TiO2−GR including enhancement of adsorptivity of pollutants, light absorption intensity, electron−hole pairs lifetime, and extended light absorption range have also been found in the composite of TiO2 and carbon nanotubes (TiO2−CNT). These strongly manifest that TiO2−GR is in essence the same as other TiO2−carbon (carb...
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paper_title: Self-assembly of nitrogen-doped TiO2 with exposed {001} facets on a graphene scaffold as photo-active hybrid nanostructures for reduction of carbon dioxide to methane

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Tailored synthesis of well-defined anatase TiO2-based crystals with exposed {001} facets has stimulated incessant research interest worldwide due to their scientific and technological importance. Herein, anatase nitrogen-doped TiO2 (N-TiO2) nanoparticles with exposed {001} facets deposited on the graphene (GR) sheets (N-TiO2-001/GR) were synthesized for the first time via a one-step solvothermal synthetic route using NH4F as the morphology-controlling agent. The experimental results exemplified that GR was uniformly covered with anatase N-TiO2 nanoparticles (10–17 nm), exposing the {001} facets. The percentage of exposed {001} facets in the N-TiO2-001/GR nanocomposites was calculated to be ca. 35%. Also, a red shift in the absorption edge and a strong absorption in the visible light range were observed due to the formation of Ti-O-C bonds, resulting in the successful narrowing of the band gap from 3.23 to 2.9 eV. The photocatalytic activities of the as-prepared photocatalysts were evaluated for CO2 reduction to produce CH4 in the presence of water vapor under ambient temperature and atmospheric pressure using a low-power 15 W energy-saving daylight lamp as the visible light source—in contrast to the most commonly employed high-power xenon lamps—which rendered the process economically and practically feasible. Among all the studied photocatalysts, the N-TiO2-001/GR nanocomposites exhibited the greatest CH4 yield of 3.70 μmol·gcatalyst −1, approximately 11-fold higher activity than the TiO2-001. The enhancement of photocatalytic performance was ascribed to the effective charge anti-recombination of graphene, high absorption of visible light region and high catalytic activity of {001} facets relative to the {101} facets.
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paper_title: A high-performance supercapacitor based on fullerene C60 whisker and polyaniline emeraldine base composite

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Fullerene C60 whisker (FW)/polyaniline emeraldine base (PANI-EB) composite with corrugated surface morphology is prepared by mixing toluene suspension of FW and PANI-EB/N-methyl-2-pyrrolidone colloid directly. A mechanism for the formation of charge transfer complex (CTC) between FW and polyaniline emeraldine base is proposed and proved by FTIR, UV–vis spectra, XPS and measuring its energy gap data. CTC can improve the electron transfer efficiency, which is benefit for the performance when materials work as supercapacitor. Electrochemical properties are analyzed by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectra. The performance of FW/PANI-EB obtained from these methods indicates its high specific capacitance (813 Fg−1 at a current density of 1 Ag−1), low electrical resistance and good cycling stability (85.2% capacitance retention after 1500 cycles).
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paper_title: Fullerene modification CdS/TiO2 to enhancement surface area and modification of photocatalytic activity under visible light

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Abstract C60-TiO2, CdS-TiO2 and CdS-C60/TiO2 composites were prepared using a sol–gel method, and their photocatalytic activity was evaluated by measuring the degradation of methylene blue (MB) solutions under visible light. The surface area, surface structure, crystal phase and elemental identification of these composites were characterized by nitrogen adsorption isotherms, scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and UV–vis absorption spectra (UV–vis). XRD showed that the CdS-C60/TiO2 composite contained a typical single and clear anatase phase. SEM of the CdS-C60/TiO2 composites revealed a homogenous composition in the particles. EDX revealed the presence of C and Ti with strong Cd and S peaks in the CdS-C60/TiO2 composite. The degradation of dye was determined by UV–vis spectrophotometry. An increase in photocatalytic activity was observed and attributed to an increase in the photo-absorption effect by fullerene and the cooperative effect of the CdS. The advisable advance BET surface area can enhance the photo-degradation effect. The repeatability of photocatalytic activity was also tested in order to investigate the stability of C60 and CdS-C60/TiO2 composites.
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paper_title: Synthesis of C60-decorated SWCNTs (C60-d-CNTs) and its TiO2-based nanocomposite with enhanced photocatalytic activity for hydrogen production.

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A novel nanostructured carbon/TiO(2) nanocomposite photocatalyst is firstly fabricated via a facile hydrothermal process by using fullerene (C(60)) decorated single-walled carbon nanotubes (SWCNTs) as carbon source, which is denoted as C(60)-d-CNTs. The obtained nanostructured carbon/TiO(2) nanocomposites are characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectra (DRS), Raman spectra, X-ray photoelectron spectroscopy (XPS) and photoluminescence spectra (PL), and then are used as catalysts for photocatalytic hydrogen production. It is found that the kinds and contents of various carbon nanostructured materials (such as SWCNTs, C(60) and C(60)-d-CNTs) coupled with TiO(2) can significantly enhance the photoactivity for hydrogen production, and the 5 wt% C(60)-d-CNTs/TiO(2) nanocomposite exhibits the best performance. Experimental results suggest that the C(60)-d-CNTs as a novel carbon nanostructured material could be more beneficial for the photogenerated carrier separation than SWCNTs and C(60) when these carbon nanostructured materials are coupled with TiO(2).
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paper_title: Activated Carbon Modified with Carbon Nanodots as Novel Electrode Material for Supercapacitors

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The main goal of this work was to modify activated carbon (AC) with carbon nanodots (C-dots) and to explore the modified composites as electrode materials for supercapacitors. C-dots were synthesized by sonication of polyethylene glycol followed by sonochemical modification of AC matrices with the preprepared C-dots. Sonication introduces the C-dots into the pores of the AC. The effect of the introduction of the C-dots into the AC and their incorporation into the pores was studied. The porosity of the AC/C-dots and the AC reference materials was explored, as well as the impact of the C-dot loading on the performance of the electrodes comprising these AC/C-dots. It was found that the AC/C-dot electrodes demonstrate a specific capacitance of 0.185 F/cm2 (per specific electrode area), three times higher than the capacitance of unmodified AC electrodes per specific electrode’s area. It was established that the new electrode’s material, namely, AC/C-dots, exhibits very stable electrochemical behavior. Many tho...
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paper_title: Minimizing Graphene Defects Enhances Titania Nanocomposite-Based Photocatalytic Reduction of CO2for Improved Solar Fuel Production

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With its unique electronic and optical properties, graphene is proposed to functionalize and tailor titania photocatalysts for improved reactivity. The two major solution-based pathways for producing graphene, oxidation–reduction and solvent exfoliation, result in nanoplatelets with different defect densities. Herein, we show that nanocomposites based on the less defective solvent-exfoliated graphene exhibit a significantly larger enhancement in CO2 photoreduction, especially under visible light. This counterintuitive result is attributed to their superior electrical mobility, which facilitates the diffusion of photoexcited electrons to reactive sites.
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paper_title: Role of graphene/metal oxide composites as photocatalysts, adsorbents and disinfectants in water treatment: a review

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With a rapidly growing population, development of new materials, techniques and devices which can provide safe potable water continues to be one of the major research emphases of the scientific community. While the development of new metal oxide catalysts is progressing, albeit at a slower pace, the concurrent and rapid development of high surface area catalyst supports such as graphene and its functionalised derivatives has provided unprecedented promise in the development of multifunctional catalysts. Recent works have shown that metal oxide/graphene composites can perform multiple roles including (but not limited to): photocatalysts, adsorbents and antimicrobial agents making them an effective agent against all major water pollutants including organic molecules, heavy metal ions and water borne pathogens, respectively. This article presents a comprehensive review on the application of metal oxide/graphene composites in water treatment and their role as photocatalyst, adsorbent and disinfectant in water remediation. Through this review, we discuss the current state of the art in metal oxide/graphene composites for water purification and also provide a comprehensive analysis of the nature of interaction of these composites with various types of pollutants which dictates their photocatalytic, adsorptive and antimicrobial activities. The review concludes with a summary on the role of graphene based materials in removal of pollutants from water and some proposed strategies for designing of highly efficient multifunctional metal oxide/graphene composites for water remediation. A brief perspective on the challenges and new directions in the area is also provided for researchers interested in designing advanced water treatment strategies using graphene based advanced materials.
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paper_title: Carbon nanotube/titanium dioxide (CNT/TiO2) core–shell nanocomposites with tailored shell thickness, CNT content and photocatalytic/photoelectrocatalytic properties

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Abstract Combining carbon nanotubes (CNTs) with TiO 2 at the nano-scale level can promote the separation of the electron–hole charges generated upon irradiation. However, charge separation capability depends on the quality of the interfacial contact between CNTs and TiO 2 , and on the morphological and surface properties of the nanocomposites. In this study, CNT/TiO 2 nanocomposites with tailored uniform core–shell coatings were fabricated from different titania precursors (titanium ethoxide (TEOTi), titanium isopropoxide (TTIP) and titanium butoxide (TBT)) by surfactant wrapping sol–gel method. This method produces a uniform and well-defined nanometer-scale anatase titania (TiO 2 ) layer on individual CNT (multi-walled), producing a mesoporous nanocomposite film. The composites were characterized by a range of analytical techniques including TEM, XRD, BET, TGA and UV–vis to reveal the textural, crystallographic and optical properties of the composites. The nanocomposites produced from the different Ti precursors exhibited significant differences in photocatalytic activity and photocurrent within the experimental range. A thinner TiO 2 layer provides shorter distance for electron transfer to the CNT core enhancing photocatalytic activity (degradation of methylene blue). However, higher CNT content in the composites correlates with higher photocurrents. It is shown that TiO 2 film thickness is the key factor controlling electron transfer and photocatalytic activity in CNT/TiO 2 nanocomposites with a core–shell structure, when the catalyst is applied in an irradiated slurry suspension. However, it is the electronic conductivity of the nanocomposite catalyst film, which increases with CNT content that controls the rate of electron removal from the photocatalyst when it is subject to an external positive bias in an appropriate photo-electrochemical cell. Overall, the CNT/TiO 2 composite prepared from TBT performed significantly better than those prepared from TEOTi and TTIP.
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paper_title: Enhanced photoelectrochemical water splitting characteristics of TiO 2 hollow porous spheres by embedding graphene as an electron transfer channel

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Abstract The generation of renewable solar fuel through photoelectrochemical water splitting is hindered by the inability to identify the right material with the optimum optical, electrical and chemical characteristics. Herein, we demonstrate the ability to fabricate TiO2 hollow porous spheres (HPS)/graphene (Gr) hybrid composite photoanodes for use in solar fuel generation cells. The fabricated materials were characterized by X-ray diffraction, Raman spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence (PL), scanning electron microscopy and electrochemical techniques. Upon the use of the TiO2 HPS/Gr photoanodes to split water photoelectrochemically under AM 1.5 illumination in 1.0 M KOH aqueous electrolyte, the performance increased with increasing the Gr content, showing a ten-fold increase in the photocurrent for the photoanode containing 5% Gr (1.449 mA cm−2) as compared to bare TiO2 HPS (0.143 mA cm−2). This enhancement is attributed to the effect of Gr in suppressing the recombination of charge carriers, as supported by the PL measurements and the decrease in the dark current upon the addition of Gr, which acts as an electron acceptor and transports electrons more efficiently. Moreover, the transient photocurrent (J–t) tests confirm the stability of the hybrid photoanodes.
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paper_title: One-step hydrothermal synthesis of Bi-TiO2 nanotube/graphene composites: An efficient photocatalyst for spectacular degradation of organic pollutants under visible light irradiation

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Abstract In the present study, we have adopted a simple one-pot alkaline hydrothermal route to synthesize Bi-doped TiO2NT/graphene composites by using different wt% of Bi with an aim to achieve the excellent photocatalytic activity under visible light source. The nature of GO is changed to deoxygenated graphene with simultaneous embedding of Bi into TiO2 nanotube (TNT), during hydrothermal process. XRD and FTIR analysis confirm the successful conversion of GO to deoxygenated graphene. EPR analysis reveals the co-existence of Ti3+ ion with oxygen vacancy, which is created by the Bi doping. The photocatalytic activity of the prepared samples is measured by the degradation of aqueous suspensions of methylene blue (MB) and Dinoseb (phenolic herbicide), under visible-light irradiation. The prepared TiO2NT/graphene composite with 2-wt% bismuth (2-BTNTG) has shown the improved photocatalytic activity as compared to their counterparts. The improved photocatalytic activity is associated to the synergistic effect of graphene and Bi-TNT, which facilitate the interfacial charge transfer and enhances the efficiency of light harvesting in the visible region. Moreover, the underlying mechanism involving photocatalytic degradation of organic pollutants over 2-BTNTG is explored by using trapping experiments, suggesting that the .OH radicals solely contributed to degradation.
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paper_title: Enhanced photocatalytic activity of bimodal mesoporous titania powders by C60 modification

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In this work, fullerene modified TiO(2) nanocomposites (denoted as C(60)/TiO(2)) with low C(60) loadings (0-1.5 wt.%) have been prepared by a simple hydrothermal method using tetrabutylorthotitanate (TBOT, Ti(OC(4)H(9))(4)) as the titanium precursor. The as-prepared C(60)/TiO(2) nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, UV-visible spectrophotometry, nitrogen adsorption, and X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy. The formation of hydroxyl radicals (˙OH) on the surface of UV-illuminated TiO(2) is probed by photoluminescence using terephthalic acid as a probe molecule. Our results have demonstrated that C(60) molecules can be dispersed as a monolayer onto bimodal mesoporous TiO(2)via covalent bonding. The photocatalytic oxidation rate of gas-phase acetone over C(60)/TiO(2) nanocomposites is greater than that over pure TiO(2), commercial Degussa P25 (P25) and C(60)-TiO(2) counterparts prepared by simple impregnating mixing. In particular, 0.5 wt.% C(60)/TiO(2) nanocomposites show the greatest photocatalytic activity with the rate constant k exceeding that of P25 by a factor of 3.3. Based on the results of the current study, we propose that C(60) molecules doped onto TiO(2) act as "electron acceptors" responsible for the efficient separation of photogenerated charge carriers and the enhancement of photocatalytic activity. The proposed mechanism for the observed photocatalytic performance of C(60)/TiO(2) nanocomposites is further corroborated by experiments on hydroxyl radical and transient photocurrent response.
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paper_title: Interactions between Carbon Nanomaterials and Biomolecules

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Interactions between carbon nanomaterials, including carbon dots, fullerene, carbon nanotube, graphene, and graphene oxide, and biomolecules play an important role in the field of nanobiotechnology. Due to the unique properties of carbon nanomaterials and the magnificent features of their colloids, it shows high potential in fibrillation inhibition, high sensitivity sensor fabrication, bioimaging, drug delivery, and other areas. Hereby, we will go over different families of carbon nanomaterials regarding to the interaction between carbon nanomaterials and biomolecules at the interface, and their applications will be reviewed as well.
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paper_title: Characterization and mechanism analysis of graphite/C-doped TiO2 composite for enhanced photocatalytic performance

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Graphite/C-doped TiO2 composite was synthesized through a modified sol–gel reaction. DRS results indicated that light absorbance edge of graphite/C-doped TiO2 was clearly red-shifted to visible light region by doping with C. SPS results displayed that separation efficiency of photoinduced charge carriers of graphite/C-doped TiO2 were greatly increased by coupling with graphite. Moreover, the photocatalytic performance of composite was evaluated by the degradation of methyl orange (MO). Results showed that graphite/C-doped TiO2 exhibited higher photocatalytic activity for MO than that of pristine TiO2 and P25, which was mainly attributed to the high crystallization, large surface hydroxyl groups, intense visible light absorption and effective separation of photoinduced charge carriers.
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paper_title: Smart Utilization of Carbon Dots in Semiconductor Photocatalysis

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Efficient capture of solar energy will be critical to meeting the energy needs of the future. Semiconductor photocatalysis is expected to make an important contribution in this regard, delivering both energy carriers (especially H2) and valuable chemical feedstocks under direct sunlight. Over the past few years, carbon dots (CDs) have emerged as a promising new class of metal-free photocatalyst, displaying semiconductor-like photoelectric properties and showing excellent performance in a wide variety of photoelectrochemical and photocatalytic applications owing to their ease of synthesis, unique structure, adjustable composition, ease of surface functionalization, outstanding electron-transfer efficiency and tunable light-harvesting range (from deep UV to the near-infrared). Here, recent advances in the rational design of CDs-based photocatalysts are highlighted and their applications in photocatalytic environmental remediation, water splitting into hydrogen, CO2 reduction, and organic synthesis are discussed.
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paper_title: Ni-doped ZnS decorated graphene composites with enhanced photocatalytic hydrogen-production performance

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Abstract This study investigated the abilities of photocatalytic H 2 production by Ni-doped ZnS-graphene composite photocatalysts. Undoped or Ni-doped ZnS was loaded on the surface of graphene to prepare a series of composite photocatalysts. Properties of the photocatalysts were characterized by field-emission scanning electron microscope (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), ultraviolet–visible diffuse reflectance spectroscopy (DRS), photoinduced current, and photocatalytic hydrogen evolution test. The as-prepared graphene@Ni-doped ZnS nanocomposites are highly active photocatalysts for hydrogen evolution and the highest photocatalytic activity reaches 8683 μmol h −1 g −1 . Effects of introducing graphene, doping, and decorated ZnS on the surface chemistry, crystalline property, optical property, surface morphology, and photocatalytic hydrogen production performance were studied. Ni-doping and decorated ZnS on graphene improved the photocatalytic H 2 production activity because of improved dispersing property, increased surface area, increased absorption, and enhanced transfer of photogenerated electrons.
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paper_title: Photocatalytic Water Splitting: Recent Progress and Future Challenges

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Water splitting to form hydrogen and oxygen using solar energy in the presence of semiconductor photocatalysts has long been studied as a potential means of clean, large-scale fuel production. In general, overall water splitting can be achieved when a photocatalyst is modified with a suitable cocatalyst. It is therefore important to develop both photocatalysts and cocatalysts. In the past five years, there has been significant progress in water splitting photocatalysis, especially in the development of cocatalysts and related physical and materials chemistry. This work describes the state of the art and future challenges in photocatalytic water splitting, with a focus on the recent progress of our own research.
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paper_title: Preparation of Core-Shell-Structured Nanoparticles (with a Noble-Metal or Metal Oxide Core and a Chromia Shell) and Their Application in Water Splitting by Means of Visible Light

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Core-shell-structured nanoparticles, consisting of a noble metal or metal oxide core and a chromia (Cr(2)O(3)) shell, were studied as promoters for photocatalytic water splitting under visible light. Core nanoparticles were loaded by impregnation, adsorption or photodeposition onto a solid solution of gallium nitride and zinc oxide (abbreviated GaN:ZnO), which is a particulate semiconductor photocatalyst with a band gap of approximately 2.7 eV, and a Cr(2)O(3) shell was formed by photodeposition using a K(2)CrO(4) precursor. Photodeposition of Cr(2)O(3) on GaN:ZnO modified with a noble metal (Rh, Pd and Pt) or metal oxide (NiO(x), RuO(2) and Rh(2)O(3)) co-catalyst resulted in enhanced photocatalytic activity for overall water splitting under visible light (lambda>400 nm). This enhancement in activity was primarily due to the suppression of undesirable reverse reactions (H(2)-O(2) recombination and/or O(2) photoreduction) and/or protection of the core component from chemical corrosion, depending on the core type. Among the core materials examined, Rh species exhibited relatively high performance for this application. The activity for visible-light water splitting on GaN:ZnO modified with an Rh/Cr(2)O(3) core-shell configuration was dependent on both the dispersion of Rh nanoparticles and the valence state. In addition, the morphology of the Cr(2)O(3) photodeposits was significantly affected by the valence state of Rh and the pH at which the photoreduction of K(2)CrO(4) was conducted. When a sufficient amount of K(2)CrO(4) was used as the precursor and the solution pH ranged from 3 to 7.5, Cr(2)O(3) was successfully formed with a constant shell thickness (approximately 2 nm) on metallic Rh nanoparticles, which resulted in an effective promoter for overall water splitting.
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paper_title: New photocatalyst BiOCl/BiOI composites with highly enhanced visible light photocatalytic performances

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BiOCl/BiOI composites with a visible light response were prepared by a simple hydrothermal method. Even though both single BiOCl and BiOI show low photocatalytic activity, BiOCl/BiOI composites provide enhanced efficiency in decomposing organic compounds including Methyl Orange (MO) and Rhodamine B (RhB). Furthermore, the 20%BiOCl/BiOI composite shows the highest efficiency for decomposing MO, while the highest performance is observed for the degradation of RhB over 70%BiOCl/BiOI composite. A possible photocatalytic mechanism has been proposed based on the relative experiments and the band positions of BiOCl and BiOI.
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paper_title: Low-Temperature Synthesis and High Visible-Light-Induced Photocatalytic Activity of BiOI/TiO2 Heterostructures

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BiOI/TiO2 heterostructures with different Bi to Ti molar ratios were synthesized through a simple soft-chemical method at a temperature as low as 80 °C. The as-prepared powders were characterized by X-ray powder diffraction, electron microscopy, UV−vis diffuse reflectance spectroscopy, nitrogen sorption, and X-ray photoelectron spectroscopy. The photocatalytic activities of these BiOI/TiO2 heterostructures were evaluated on the degradation of methyl orange under visible-light irradiation (λ > 420 nm). The results revealed that the BiOI/TiO2 heterostructures exhibited much higher photocatalytic activities than pure BiOI and TiO2, respectively, and 50%BiOI/TiO2 showed the best activity among all these heterostructured photocatalysts. Surface photovoltage spectroscopy and transient photovoltage measurements were used to confirm the formation of heterojunction and probe charge transfer between BiOI and TiO2. The visible-light photocatalytic activity enhancement of BiOI/TiO2 heterostructures could be attribute...
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paper_title: Visible light driven type II heterostructures and their enhanced photocatalysis properties: a review

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Considerable efforts have been devoted to enhancing the photocatalytic activity and solar energy utilization of photocatalysts. The fabrication of type II heterostructures plays an important role in photocatalysts modification and has been extensively studied. In this review, we briefly trace the application of type II heterostructured semiconductors in the area of environmental remediation and water splitting, summarize major fabrication methods, describe some of the progress and resulting achievements, and discuss the future prospects. The scope of this review covers a variety of type II heterostructures, focusing particularly on TiO2 and ZnO based visible light driven type II 0D and 1D heterostructured photocatalysts. Some other low dimensional nanomaterials which have shown high-performance photocatalysis are also presented. We expect this review to provide a guideline for readers to gain a clear picture of fabrication and application of type II heterostructures.
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paper_title: State-of-the-Art Progress in Diverse Heterostructured Photocatalysts toward Promoting Photocatalytic Performance

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Semiconductor photocatalysts have received much attention in recent years due to their great potentials for the development of renewable energy technologies, as well as for environmental protection and remediation. The effective harvesting of solar energy and suppression of charge carrier recombination are two key aspects in photocatalysis. The formation of heterostructured photocatalysts is a promising strategy to improve photocatalytic activity, which is superior to that of their single component photocatalysts. This Feature Article concisely summarizes and highlights the state-of-the-art progress of semiconductor/semiconductor heterostructured photocatalysts with diverse models, including type-I and type-II heterojunctions, Z-scheme system, p–n heterojunctions, and homojunction band alignments, which were explored for effective improvement of photocatalytic activity through increase of the visible-light absorption, promotion of separation, and transportation of the photoinduced charge carries, and enhancement of the photocatalytic stability.
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paper_title: Dual Cocatalysts Loaded Type I CdS/ZnS Core/Shell Nanocrystals as Effective and Stable Photocatalysts for H2 Evolution

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The photocatalytic activity and stability of nanocrystals (NCs) are two important issues for their application in photocatalysis. In this work, we report a combined method to promote the photocatalytic activity as well as the stability of CdS NCs for photocatalytic H2 evolution. ZnS shell was grown on CdS NCs forming type I core/shell CdS/ZnS nanocrystals (NCs) to restrain the photocorrosion and passivate the trap states on CdS NCs. Thereafter, dual cocatalysts were loaded to promote the separation and transfer of electrons and holes from the core to outer surface for photocatalytic reactions. It is found that Pt and Ni are effective reduction cocatalysts (RCs) while PdS and PbS are effective oxidation cocatalysts (OCs) for promoting the charge separation and transfer. This strategy was also proved to be effective for other type I core/shell NCs, such as CdTe/CdS/ZnS NCs.
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paper_title: Synthesis and Catalytic Applications of Non-Metal Doped Mesoporous Titania

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Mesoporous titania (mp-TiO2) has drawn tremendous attention for a diverse set of applications due to its high surface area, interfacial structure, and tunable combination of pore size, pore orientation, wall thickness, and pore connectivity. Its pore structure facilitates rapid diffusion of reactants and charge carriers to the photocatalytically active interface of TiO2. However, because the large band gap of TiO2 limits its ability to utilize visible light, non-metal doping has been extensively studied to tune the energy levels of TiO2. While first-principles calculations support the efficacy of this approach, it is challenging to efficiently introduce active non-metal dopants into the lattice of TiO2. This review surveys recent advances in the preparation of mp-TiO2 and their doping with non-metal atoms. Different doping strategies and dopant sources are discussed. Further, co-doping with combinations of non-metal dopants are discussed as strategies to reduce the band gap, improve photogenerated charge separation, and enhance visible light absorption. The improvements resulting from each doping strategy are discussed in light of potential changes in mesoporous architecture, dopant composition and chemical state, extent of band gap reduction, and improvement in photocatalytic activities. Finally, potential applications of non-metal-doped mp-TiO2 are explored in water splitting, CO2 reduction, and environmental remediation with visible light.
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paper_title: Synergy of metal and nonmetal dopants for visible-light photocatalysis: a case-study of Sn and N co-doped TiO2

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This paper mainly focuses on the synergistic effect of Sn and N dopants to enhance the photocatalytic performance of anatase TiO2 under visible light or simulated solar light irradiation. The Sn and N co-doped TiO2 (SNT-x) photocatalysts were successfully prepared by the facile sol-gel method and the post-nitridation route in the temperature range of 400-550 °C. All the as-prepared samples were characterized in detail by X-ray diffraction, UV-vis diffuse reflectance spectroscopy, transmission electron microscopy, X-ray photoelectron and electron spin resonance spectroscopy and photoelectrochemical measurements. The characterization results reveal that the co-incorporation of Sn and N atoms remarkably modifies the electronic structure of TiO2, which gives rise to a prominent separation of photogenerated charge carriers and more efficient interfacial charge-transfer reactions in a photocatalytic process. The enhanced photocatalytic activity is attributed to the intensified active oxygen species including hydroxyl radicals (˙OH) and superoxide anion radicals (O2˙(-)) for degradation of organic pollutants. And the result of photocatalytic hydrogen production further confirms the existence of the synergistic effect in the SNT-x samples, because they exhibit higher photocatalytic activity than the sum of N/TiO2 and Sn/TiO2. This work provides a paradigm to consolidate the understanding of the synergistic effect of metal and non-metal co-doped TiO2 in domains of photocatalysis and photoelectrochemistry.
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paper_title: Chemical Vapor Deposition of Thin Crystals of Layered Semiconductor SnS2 for Fast Photodetection Application

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Layered two-dimensional (2D) semiconductors, such as MoS2 and SnS2, have been receiving intensive attention due to their technological importance for the next-generation electronic/photonic applications. We report a novel approach to the controlled synthesis of thin crystal arrays of SnS2 at predefined locations on chip by chemical vapor deposition with seed engineering and have demonstrated their application as fast photodetectors with photocurrent response time ∼5 μs. This opens a pathway for the large-scale production of layered 2D semiconductor devices, important for applications in integrated nanoelectronic/photonic systems.
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paper_title: Temperature-Mediated Selective Growth of MoS2/WS2 and WS2/MoS2 Vertical Stacks on Au Foils for Direct Photocatalytic Applications

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A growth-temperature-mediated two-step chemical vapor deposition strategy is designed to synthesize MoS2 /WS2 and WS2 /MoS2 stacks on Au foils. Predominantly A-A stacked MoS2 /WS2 and A-B stacked WS2 /MoS2 are selectively achieved and confirmed. Relative enhancements or reductions in photocatalytic activities of MoS2 /WS2 or WS2 /MoS2 are observed under illumination, because the type-II band alignment enables directional electron flow from electrode to active site.
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paper_title: Characterization of thin TiO2 films prepared by plasma enhanced chemical vapour deposition for optical and photocatalytic applications

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Abstract Thin titanium oxide films were deposited using a radio frequency (RF) plasma enhanced chemical vapour deposition method. Their optical properties and thickness were determined by means of ultraviolet–visible absorption spectrophotometry. Films of the optical parameters very close to those of titanium dioxide have been obtained at the high RF power input. Their optical quality is high enough to allow for their use in a construction of stack interference optical filters. At the same time, these materials exhibit strong photocatalytic effects. The results of structural analysis, carried out by Raman Shift Spectroscopy, show that the coatings posses amorphous structure. However, Raman spectra of the same films subjected to thermal annealing at 450 °C disclose an appearance of a crystalline form, namely that of anatase. Surface morphology of the films has also been characterized by Atomic Force Microscopy revealing granular, broccoli-like topography of the films.
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paper_title: Synthesis and Microstructural Characterization of SnO2:F Thin Films Deposited by AACVD

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In this work, we report the synthesis and microstructural characterization of Tin oxide thin films doped with fluorine for applications such as transparent conductive oxides. Tin oxide doped with fluorine thin films were deposited by aerosol assisted chemical vapor deposition technique onto a borosilicate glass substrate, using a precursor solution of stannic chloride in ethanol and ammonium fluoride as the dopant. Deposition temperature was varied between 623-773 K. Also, other deposition parameters such as concentration of the precursor solution and gas carrier flux were fixed at 0.1 mol∙dm-3 and 5 L min-1 respectively. Results indicate the presence of only the cassiterite phase of Tin oxide in all samples. Thin films obtained were characterized by X-Ray Diffraction. Surface morphology and microstructure were studied by field emission scanning electron microscopy, optical properties of samples were analyzed by total transmittance and reflectance spectra. The resistivity value of the films was measured by the sheet resistance.
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paper_title: Combinatorial aerosol assisted chemical vapour deposition of a photocatalytic mixed SnO2/TiO2 thin film

paper_content:

Combinatorial Aerosol Assisted Chemical Vapour Deposition (cAACVD) was used to grow a thin film that graduated across its width from tin dioxide to titanium dioxide. This is a relatively new technique that can be used to create a variety of mixed phase and composition thin films on a single substrate. Here cAACVD was used to deposit a mixed phase TiO2 and SnO2 film and composition was related to UV photocatalysis, hydrophobicity and microstructure not inherent to anatase TiO2 or cassiterite SnO2. Characterisation was achieved using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and UV-Vis spectroscopy. Functional testing to elucidate the differences in functional properties across the film was undertaken by the photo-induced degradation of a resazurin ‘intelligent’ ink, a photo-induced wettability study and two-point resistivity measurements. Functional properties showed enhanced photocatalysis in comparison to Pilkington Activ™ with similar formal quantum yield (molecules destroyed per absorbed photon) and formal quantum efficiency (molecules destroyed per incident photon) values.
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paper_title: Production of aligned carbon nanotubes by the CVD injection method

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High purity, aligned multi-walled carbon nanotubes films were grown on quartz substrates by injecting a solution of ferrocene in toluene. The injection CVD method allows excellent control of the catalyst to carbon ratio. The nanotube diameter, length and alignment were controlled by varying the reaction parameters. In particular, the effects of temperature, catalyst concentration and reaction time have been investigated.
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paper_title: Highly Transparent Wafer-Scale Synthesis of Crystalline WS2 Nanoparticle Thin Film for Photodetector and Humidity-Sensing Applications.

paper_content:

In the present investigation, we report a one-step synthesis method of wafer-scale highly crystalline tungsten disulfide (WS2) nanoparticle thin film by using a modified hot wire chemical vapor deposition (HW-CVD) technique. The average size of WS2 nanoparticle is found to be 25–40 nm over an entire 4 in. wafer of quartz substrate. The low-angle XRD data of WS2 nanoparticle shows the highly crystalline nature of sample along with orientation (002) direction. Furthermore, Raman spectroscopy shows two prominent phonon vibration modes of E12g and A1g at ∼356 and ∼420 cm–1, respectively, indicating high purity of material. The TEM analysis shows good crystalline quality of sample. The synthesized WS2 nanoparticle thin film based device shows good response to humidity and good photosensitivity along with good long-term stability of the device. It was found that the resistance of the films decreases with increasing relative humidity (RH). The maximum humidity sensitivity of 469% along with response time of ∼12 ...
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paper_title: Aerosol assisted chemical vapour deposition of a ZrO2–TiO2 composite thin film with enhanced photocatalytic activity

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ZrO2–TiO2 composite thin films were deposited by aerosol assisted chemical vapour deposition onto a glass substrate at 450 °C and then annealed at 600 °C. For comparison ZrO2 thin films and TiO2 thin films were deposited under the same conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), UV-Vis and Raman spectroscopy were used to characterize all films. Photocatalytic activities were tested by degradation of intelligent ink containing resazurin redox dye under UVA irradiation. The formal quantum efficiency (FQE) and yield (FQY) for the ZrO2–TiO2 composite thin films were determined as 2.03 × 10−3 dye molecules per incident photon and 4.91 × 10−3 dye molecules per absorbed photon respectively. Surprisingly the ZrO2–TiO2 composite was a more efficient photocatalyst than the comparable TiO2 coating.
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paper_title: A new supported TiO2 film deposited on stainless steel for the photocatalytic degradation of contaminants of emerging concern

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Abstract A new supported catalyst composed of a nanostructured TiO 2 film deposited on a stainless steel mesh (nanoTiO 2 -SS) using the Metal Organic Chemical Vapour Deposition (MOCVD) technique was evaluated for the photocatalytic degradation of a mixture of contaminants of emerging concern. Results showed that under the oxidative conditions tested, the nanoTiO 2 -SS catalyst demonstrated an efficiency in degrading the target contaminants higher than that observed under direct photolysis and photocatalysis using the conventional TiO 2 Degussa P25 catalyst at the same amount of TiO 2 participating to the photocatalysis. Specifically, the rate of removal of warfarin and trimethoprim obtained with the new catalyst was found twice the one observed by using TiO 2 Degussa P25 and approximately 1.6 times faster for metoprolol, carbamazepine and gemfibrozil. An evaluation of the electrical energy per order magnitude of removal (EE/O) confirmed the enhanced performance of the new catalyst (24.3–31.8 kWh m −3 rather than 32.8–39.3 kWh m −3 for conventional TiO 2 ) and that the performance is compound-dependent. Toxicity testing revealed that some assays are suitable for the investigation of bioactivity of treated waters containing contaminants of emerging concern at μg L −1 level. Specifically, the AMES Fluctuation Test, Fish Embryo Acute Toxicity Test and Green alga Selenastrum capricornutum test provided valuable results for an environmental impact assessment. On the other hand, the Daphnia magna and Vibrio fischeri acute toxicity tests were not sensitive enough to detect bioactivity in the samples analysed without prior pre-concentration.
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paper_title: Nano ZnO synthesis by modified sol gel method and its application in heterogeneous photocatalytic removal of phenol from water

paper_content:

Abstract Zinc oxide nanoparticles were synthesized by precipitation and modified sol gel methods. The influence of calcination temperature on morphology and crystallite size of ZnO was studied by varying temperature from 400 to 700 °C. The nano-structured ZnO particles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDXS) and tranmission electron microscopy (TEM). The photo catalytic activity of as-prepared ZnO was evaluated by degradation of phenol under UV laser irradiation. The Photocatalytic degradation (PCD) efficiency of ZnO was found to decrease with the increase in calcination temperature due to agglomeration of particles and the increase in particle size. In addition to the effect of calcination temperature, the influence of various other parameters such as photocatalyst concentration, initial pH and the initial phenol concentration was also investigated to achieve the maximum PCD of phenol. The operational parameters show the expected influence regarding the efficiency of the photocatalytic degradation process. The results follow the pseudo-first order rate kinetics.
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paper_title: Effects of pH and Temperature on Sol-Gel Processing within the Pbo-TiO2 System

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Effects of sol formation temperature and pH value on sol-gel processing within the PbO-TiO2 system were investigated. PbO-TiO2 gels were prepared from the mixed solution of lead nitrate and titanium tetrachloride at 30° to 70°C under various pH values of 1.0 to 10.8, and dehydrated at 60° to 80°C for 72 h under vacuum. The dried gels are amorphous. The crystalline phases of the products after calcination at 70°C for 1 h in air are dependent upon the sol formation conditions as follows: (l)TiO2:30°C, pH 1.0 to 4.6; and 40° C, pH l.0 to 2.O. (2) PbTi3O7:50° to 70°C, pH 1.0 to 4.6. (3) PbTiO3: 70°C, pH 8.0 to 10.8. (4) PbTiO3 and traces of PbTi3O7: 30° to60°C, pH 7.1 to 10.8.
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paper_title: Effect of Calcination Temperature of Carbon Doped TiO2 (C-TiO2) on Photocatalytic Activity under Visible Light

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Carbon doped TiO2 was prepared by solgel method using titanium isopropoxide and acetylacetone as the precursors for titanium and carbon respectively. Systematic studies on the calcination temperature and its impact on surface properties and photocatalytic activities under visible light was investigated. The dopant concentration was fixed at 0.75% and the calcinations temperature was varied from 450 to 750oC.The prepared photocatalysts were characterized by XRD, UV-Vis DRS and FESEM in order to understand the relationship between the properties and its photocatalytic activities. The photocatalytic activity was measured by carrying out a standard photodegradation test under domestic illumination lamp with methylene blue as the model pollutant. With three hours of irradiation time, 69.7% of methylene blue was removed by C-TiO2 which was calcined at an optimum temperature of 600°C.
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paper_title: Porphyrin/SiO2/Cp*Rh(bpy)Cl Hybrid Nanoparticles Mimicking Chloroplast with Enhanced Electronic Energy Transfer for Biocatalyzed Artificial Photosynthesis

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A biocatalyzed artificial photosynthesis system (APS) based on porphyrin/SiO2/Cp*Rh(bpy)Cl hybrid nanoparticles (TCPP/SiO2/Rh HNPs) to mimic chloroplasts in green plant is reported. The TCPP/SiO2/Rh HNPs are fabricated via sol-gel reaction of silica precursors functionalized with photosensitizer (porphyrin, TCPP) and electron mediator (Cp*Rh(bpy)Cl, M); while the integration of enzyme and coenzyme nicotinamide adenine dinucleotide (NAD)(H), on the outer surface of the HNPs is achieved through electro-static-interaction-driven assembling under the entanglement of a negatively charged polyelectrolyte. The chloroplast-mimicking, highly integrated APS exhibits remarkably superior performance over a free system such that the regeneration of NADH is improved from 11% to 75%, and the synthesis of formic acid from CO2 increased from 15 to 100 mu mol. Based on the detailed investigations into the photochemical and electrochemical properties, it is speculated that the covalent linking of the photosensitizer and electron mediator via silicon hydride bonds, and the formed SiO2 network through sol-gel reaction, may form intramolecular and intermolecular electron transfer chains to direct more efficient electron transfer from TCPP to M. Such intramolecular and intermolecular electrons and energy transfer, cooperated with the integrated biocatalytic process, lead to the significantly enhanced overall reaction efficiency. Moreover, the integrated APS also allows facile recycling of expensive M, enzymes, and cofactors.
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paper_title: The effects of Fe, Co and Ni dopants on TiO2 structure of sol–gel nanopowders used as photocatalysts for environmental protection: A comparative study

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This paper highlights the effects of iron, cobalt and nickel dopants on the structure and photocatalytic properties of the sol–gel TiO2 nanopowders and performs a comparative study of their behavior. Undoped TiO2 and 0.5, 1 and 2 wt% Fe, Co and/or Ni-doped TiO2 nanopowders have been prepared. The compositions with 0.5 wt% dopant were selected for this study considering that the best results have been obtained using iron dopant with this concentration. A detailed XRD analysis, based on an own calculus program, has established the lattice parameters, the average size of the crystallites (D), the unit cell volume (UCV) and the average lattice strains (S), which can give some information about the structural disorder. The structural changes due to the thermal treatment and the type of the dopant were established. The dopants addition is responsible for supplementary defects in the crystalline lattice. Besides the mobile single point defects due to the thermal treatment, the dopants induce the paramagnetic ones. The increase of temperature does not significantly influence the unit cell volume (UCV). This fact could be considered as a proof of the acceptance of the dopant by the anatase lattice, where MexTi1–xO2–δ type solid solutions are formed. The variation of the (D) and (S) values with temperature, calculated for both undoped and doped TiO2 samples indicates the fact that the highest disorder state was found at 400 °C. The photocatalytic activity of the prepared nanopowders has been tested in the degradation of nitrobenzene from water. The sample with 0.5 wt% Fe dopant concentration thermally treated at 400 °C presented the best photocatalytic activity.
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paper_title: Novel continuous single-step synthesis of nitrogen-modified TiO 2 by flame spray pyrolysis for photocatalytic degradation of phenol in visible light

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Abstract A novel rapid and continuous process has developed for the synthesis of nitrogen-doped TiO2 (N-TiO2) with flame spray pyrolysis (FSP) method. The nitrogen incorporation into TiO2 was achieved by a facile modification (addition of dilute nitric acid) in the precursor for the synthesis. The catalysts were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. The doping of nitrogen into the TiO2 was confirmed by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray (EDX) spectroscopy. The UV–vis spectra of the modified catalysts (with primary N source) exhibited band-gap narrowing for 4N-TiO2 with band gap energy of 2.89 eV, which may be due to the presence of nitrogen in TiO2 structure. The introduction of secondary N-source (urea) into TiO2 crystal lattice results in additional reduction of the band gap energy to 2.68 eV and shows a significant improvement of visible light absorption. The N-TiO2 nanoparticles modified by using secondary N-source showed significant photocatalytic activity under visible light much higher than TiO2. The higher activity is attributed to the synergetic interaction of nitrogen with the TiO2 lattice. The lowering of the band-gap energy for the flame made N-doped TiO2 materials implies that the nitrogen doping in TiO2 by aerosol method is highly effective in extending the optical response of TiO2 in the visible region. The nitrogen atomic percentage has increased monotonically (0.09%–0.15%) with the increase in primary nitrogen source (nitric acid), and significantly boosted to 0.97% when secondary nitrogen source (urea) was introduced. The highest rate of phenol degradation was obtained for catalysts with secondary N source due to increase in N content in the catalyst.
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paper_title: Band gap engineering of CuS nanoparticles for artificial photosynthesis

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Abstract CuS nanoparticles with engineered optical band gap that varies with substrate temperature were prepared by spray-pyrolysis technique. Structural, morphological, and optical characterization of the as-synthesized CuS nanoparticles was done through X-ray diffraction, field-emission scanning electron microscopy, Raman spectroscopy, photoluminescence spectroscopy, and ultraviolet–visible spectroscopy. This work provides a convenient method of tuning of the band gap for particular applications. We tuned the band gap of the as-synthesized CuS nanoparticles to fall within the wavelength range of 325–350 nm. We propose their use as light harvesting antenna in artificial photosynthesis.
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paper_title: Novel one-step synthesis of sulfur doped-TiO2 by flame spray pyrolysis for visible light photocatalytic degradation of acetaldehyde

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Abstract Novel one-step synthesis route for S-doped TiO 2 photocatalysts by flame spray pyrolysis (FSP) for visible light photocatalysis was developed. We observed improved visible light absorption and reduction of the band gap energies to 2.78 eV. Addition of sulfur in the TiO 2 promoted the anatase to rutile transformation in the prepared catalysts. The S oxidation states along with optical properties of the catalyst were studied using X-ray photoelectron spectroscopy (XPS) and UV–Vis spectroscopy. The oxidation state of the S atoms incorporated into the TiO 2 is determined to be mainly S 4+ and S 6+ in the XPS spectra. Among all the synthesized catalysts, catalyst with 2 M sulfuric acid in precursor illustrated an impressive performance for the visible light induced photocatalysis along with higher S 6+ /S 4+ of 5.61. The S +6 presence has important role in enhancing the visible light photocatalytic activity. The photocatalytic activity of the sulfur-doped TiO 2 was evaluated through the degradation of acetaldehyde under visible light irradiation. Our results show that we developed a new synthesis method to achieve stable and highly efficient solar light-driven S-modified TiO 2 photocatalysts for water purification.
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paper_title: Gold And Nitrogen co-doped TiO2 Nanoparticles Synthesized By Laser Pyrolysis, Application In Photocatalysis

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During the last ten years, TiO2 has been intensively investigated as a potential photocatalyst for degradation of water pollutants. Such interest is due to high stability, nontoxicity and optical properties, making it suitable for applications such “as self-cleaning windows, anti-bacterial coating and waste water purification [1,2]”. In water treatment, a key issue is the synthesis of photocatalysts with good efficiency both in the UV and the visible range. In this context “doping” titania with metallic ions (for example Au) leads to photocatalyst with improved efficiency compared to pure TiO2, this effect was attributed to better charge transfer. Moreover, gold supported titania nanoparticles present an absorption under visible light irradiation attributed to the surface plasmon resonance [3].. ::: In this context, the Laser pyrolysis [4] method appears as a convenient way to prepare various nanoparticles (NPs) or “doped” NPs in a one step process.This versatile method is used for efficient production of nanoparticles with precise chemical composition, size, cristallinity,... It is based on the interaction of a high power infrared laser beam with precursors. For TiO2 synthesis, titanium tetraisopropoxide (TTIP) is used as precursor. It is decomposed in an incandescent flame observed in the laser-precursor interaction zone where NPs nucleate and grow. Their characteristics are controlled by the choice of experimental parameters; in particular the size of the nanoparticles depends on the residence time in the laser beam controlled by the gas flow rate of reactants in the reaction zone. The cristallinity is controlled by the reaction temperature in the reaction zone, i.e. the laser power. The chemical composition also depends on the nature of the different reagents in the precursor mixture: TiO2 is obtained from pure TTIP, nitrogen doped TiO2 is obtained from TTIP by adding a slight flow of NH3, Au-TiO2 is obtained from a mixture of TTIP+HAuCl4.3H2O. All the nanoparticles were characterized by XDR, HRTEM (see picture below), UV-Vis measurements,…Both N-TiO2 and Au-TiO2 present light absorption in the visible range. ::: The photocatalytic activity of the different samples was investigated by following the degradation of formic acid as an organic model pollutant under UV and visible irradiation using UV-A lamp with maximum radiation at λ=365 nm and LEDs (400>λ<800 nm). The results prove that both TiO2 and Au-TiO2 synthesized from laser pyrolysis are more active than the reference Degussa P25 under irradiation with UV light. An enhancement of photocatalytic activity is observed by increasing gold content. However, the Au-TiO2 samples do not exhibit activity under visible light. By contrast, N-TiO2 and Au- N-TiO2, present a significant photocatalytic activity under visible light. However, the N-TiO2 is not very active under UV while the Au-N-TiO2 exhibit good efficiency under such illumination compared to pure TiO2 and gold modified TiO2. These results indicate an efficient activity under visible correlated to the presence of N together with a good activity under UV correlated to the presence of Au. These results will be discussed by comparison with the literature. ::: References ::: [1] X. Chen, SS. Mao, Nature, 238 (1972) 37 ::: [2] J-M. Hermann, C. Duchamp, C. Guillard, Journal of hazardous Materials, 146 (2007) 624. ::: [3] J. Fang, S. Cao, Z. Wang, Journal of Hydrigen Energy, 37 (2012) 17853. ::: [4] H. Maskrot, Y. Leconte, N. Herlin-Boime, Catalysis today, 116 (2006) 6.
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paper_title: One step synthesis of N-doped and Au-loaded TiO2 nanoparticles by laser pyrolysis: Application in photocatalysis

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Photocatalysis is a major tool for air and water depollution and photocatalysts with improved efficiency in the visible range are still needed. In this context, we show that N-TiO2 nanoparticles modified with Au, called Au/N-TiO2, seem to represent a good compromise: significant photocatalytic activity is observed under visible light together with an activity higher than TiO2 P25 under UV irradiation. In order to demonstrate such efficiency of the Au/N-TiO2 sample, TiO2, Au-TiO2, N-TiO2 and Au modified N-TiO2 nanoparticles were synthesized in one step using the laser pyrolysis method. The photocatalytic activity of the powders was evaluated through the photocatalytic degradation of formic acid (FA) both under UV and visible light irradiation. Under UV irradiation, all the laser-synthesized samples exhibit a high efficiency compared to commercial TiO2 P25. Moreover, the modification by Au induces an enhancement of the photocatalytic activity compared to pure TiO2 even at very low concentrations. Under visible light, the N-doped samples exhibit some photoactivity and the degradation rate of FA in presence of Au/N-TiO2 is much increased compared to N-TiO2. In conclusion, our Au/N-TiO2 sample exhibits efficiency better than P25 under UV together with an activity under visible light.
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paper_title: Influence of pH, Precursor Concentration, Growth Time, and Temperature on the Morphology of ZnO Nanostructures Grown by the Hydrothermal Method

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We investigated the influence of the pH value, precursor concentration (C), growth time and temperature on the morphology of zinc oxide (ZnO) nanostructures. The pH of the starting solution was varied from1.8 to 12.5. It was found that the final pH reaches an inherent value of 6.6 independently of the initial pH solution. Various ZnO structures of nanotetrapod-like, flower-like, and urchin-like morphology were obtained at alkaline pH (8 to 12.5) whereas for pH solution lower than 8 rod-like nanostructures occurred. Moreover, we observed the erosion of the nanorods for a pH value less than 4.6. By changing the concentrations the density and size were also varied. On going from a high (C > 400mM) to lower (C < 25mM) C, the resulted ZnO nanostructures change from a film to nanorods (NRs) and finally nanowires (NWs). It was also found that the length and diameter of ZnO NRs follow a linear relation with time up to 10 hours, above which no further increase was observed. Finally the effect of growth temperature was seen as an influence on the aspect ratio.
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paper_title: One-pot hydrothermal synthesis of ZnO-reduced graphene oxide composites using Zn powders for enhanced photocatalysis

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Abstract Zn powder was successfully utilized as a reducing agent and a precursor of ZnO for one-pot synthesis of reduced graphene oxide (rGO)–ZnO photocatalysts. Two rGO–ZnO composites were synthesized with or without a surfactant, cetyltrimethyl ammonium bromide (CTAB). The structural, morphological, and photochemical properties of the samples were thoroughly investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), N 2 adsorption/desorption, UV–vis diffuse reflectance (UV–vis DRS), thermogravimetric-differential thermal analysis (TG-DTA), and Raman spectroscopy. Zn powder could effectively reduce GO to graphene and be transformed to ZnO with the assistance of the surfactant. The surfactant was found to influence the properties of rGO–ZnO. rGO–ZnO photocatalysts could decompose methylene blue under UV–vis illumination and exhibited higher activities than pristine ZnO. The co-existence of GO–rGO would be more favorable to photocatalysis.
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paper_title: Construction of fiber-based BiVO4/SiO2/reduced graphene oxide (RGO) with efficient visible light photocatalytic activity

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The visible light-responsive photocatalyst BiVO4/SiO2/reduced graphene oxide (RGO) was synthesized by hydrothermal method. For easy collection and reuse in slurry systems, RGO/BiVO4/SiO2 was immobilized on the cotton fiber by ultrasonic-heating technology. The characterization results indicated that the surface of cotton fiber was uniformly covered with BiVO4/SiO2/RGO photocatalyst. The loaded BiVO4/SiO2/RGO endowed the composite fibers with an excellent photocatalytic activity and recyclability for the degradation of the C.I. Reactive Blue 19 under visible light irradiation. The introduction of RGO exhibited the great dispersibility of photocatalyst in aqueous solution and the high absorbance of positive metal ions, which enhanced its photocatalytic performance. Given the above research results, the flexible fiber-based BiVO4/SiO2/RGO composite would have potential applications in the water/air purification field.
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paper_title: Solvothermal synthesis of hollow flower-like Gd-doped TiO2 with enhanced photocatalytic performance

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The hollow flower-like Gd-TiO2 (FGT) photocatalytic materials have been synthesized through a facile hydrothermal process by using gadolinium nitrate hexahydrate as a Gd source. The FGT was characterized with scanning electron microscopy, transmission Electron Microscope, X-ray diffraction, X-ray photoelectron spectroscopy, and UV–Vis diffuse reflectance spectroscopy. The results show that the crystal structure of the synthesized material is rutile, the morphology is three-dimensional hollow flower-like. Gd-TiO2 material with the doping amount of 0.125 mol% exhibit an enhanced phoocatalytic activities on the degradation of RhB under simulated sunlight irradiation, which reaching to 95%. Therefore, the FGT shows favorable photocatalytic performance toward organic pollutant degaradation field.
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paper_title: Effect of Organic Solvents on Iron Oxide Nanoparticles by the Solvothermal Method

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γ-Iron oxide nanoparticles were produced by the solvothermal method at 250−300 °C. Phase identification, crystal size analysis, and morphology were performed using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The influences of iron(III) acetylacetonate concentration and reaction time on nanoparticles suggested differences in the crystallization pathway of products prepared in 1,4-butanediol and in toluene. Iron oxides prepared in 1,4-butanediol have been proposed to crystallize and precipitate from glycoxide, while those prepared in toluene are obtained by thermal decomposition of iron(III) acetylacetonate. The calcinations of nanoparticles at 350 °C indicated that iron oxides prepared in 1,4-butanediol have a higher thermal stability than those prepared in toluene due to phase transformation from γ- to α-iron oxides in samples prepared in toluene.
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paper_title: One-pot solvothermal synthesis of ZnTe/RGO nanocomposites and enhanced visible-light photocatalysis

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Abstract Zinc telluride/reduced graphene oxide (ZnTe/RGO) nanocomposites are synthesized by a one-pot, facile, solvothermal process using hydrazine hydrate as the reducing agent. Hydrazine hydrate not only promoted the formation of ZnTe nanoparticles but also reduced GO to RGO. The formation of ZnTe/RGO is demonstrated by different techniques. In addition, the experimental results suggest a possible formation mechanism of these nanocomposites. Finally, due to the transfer of the photo-generated electrons between ZnTe and RGO resulting in low electrons/holes recombination, the as-prepared nanocomposites of ZnTe/RGO exhibited strongly enhanced photocatalytic activity for the bleaching of methyl blue (MB) dye under visible light irradiation.
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paper_title: Rapid and Continuous Hydrothermal Crystallization of Metal Oxide Particles in Supercritical Water

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Hydrolysis of 10 metal salt aqueous solutions of 6 metal oxides was conducted in supercritical water. Continuous and rapid production of metal oxide fine particles was achieved by mixing a metal salt aqueous solution with preheated water fed from another line. The reaction time required was less than 2 min. Particle size, morphology, and crystal structure of the obtained metal (hydrous) oxides were examined. Particle size (20 to 600 nm) was different among the systems but the size range was relatively narrow in all the cases.
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paper_title: Solvothermal synthesis of hierarchical TiO2 nanostructures with tunable morphology and enhanced photocatalytic activity

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Abstract This paper presents controllable growth and photocatalytic activity of TiO 2 hierarchical nanostructures by solvothermal method at different temperatures. It is revealed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the morphology of TiO 2 can be effectively controlled as rose-like, chrysanthemum-like and sea-urchin-like only changing solvothermal temperature. BET surface area analysis confirms the presence of a mesoporous network in all the nanostructures, and shows high surface area at relatively high temperature. The photocatalytic activities of the photocatalysts are evaluated by the photodegradation of RhB under UV light irradiation. The TiO 2 samples exhibit high activity on the photodegradation of RhB, which is higher than that of the commercial P25. The enhancement in photocatalytic performance can be attributed to the synergetic effect of the surface area, crystallinity, band gap and crystalline size.
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paper_title: α-Fe2O3 nanosheet-assembled hierarchical hollow mesoporous microspheres: Microwave-assisted solvothermal synthesis and application in photocatalysis.

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Abstract α-Fe 2 O 3 nanosheet-assembled hierarchical hollow mesoporous microspheres (HHMSs) were prepared by thermal transformation of nanosheet-assembled hierarchical hollow mesoporous microspheres of a precursor. The precursor was rapidly synthesized using FeCl 3 ·6H 2 O as the iron source, ethanolamine (EA) as the alkali source, and ethylene glycol (EG) as the solvent by the microwave-assisted solvothermal method. The samples were characterized by X-ray powder diffraction (XRD), thermogravimetric (TG) analysis, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption–desorption isotherm. The effects of the microwave solvothermal temperature and EA amount on the morphology of the precursor were investigated. The as-prepared α-Fe 2 O 3 HHMSs exhibit a good photocatalytic activity for the degradation of salicylic acid, and are promising for the application in wastewater treatment.
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paper_title: ZnO rods/reduced graphene oxide composites prepared via a solvothermal reaction for efficient sunlight-driven photocatalysis

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Abstract Small-sized ZnO rods with an average length of ca. 180 nm and a diameter of ca. 16 nm were successfully associated to reduced graphene oxide (rGO) via a solvothermal reaction conducted in ethanol. A set of characterization including TEM, SEM, XRD, BET, Raman spectroscopy and UV–vis absorption confirm that the ZnO/rGO composite is composed of highly dispersed ZnO rods bound to rGO nanosheets. The photocatalytic activity of the ZnO/rGO composite was investigated under solar light and under visible light irradiation using the Orange II dye in aqueous solution. Results indicate that the ZnO/rGO composite containing 10 wt% rGO used under solar light irradiation exhibit the highest photocatalytic activity and that the kinetic of reduction is of pseudo-fist-order. The photocatalyst is only weakly sensitive to pH changes and to the presence of inorganic salts or to glucose in the reaction medium. In addition, the reusability of the ZnO/rGO composite was studied and the results demonstrate that the photocatalyst can be reused up to fifteen times with nearly negligible loss of activity. The high photocatalytic performances can be attributed to the high specific surface of ZnO rods, to the enhanced visible light absorption of the ZnO/rGO composite and to the strong decrease of charge carrier recombinations originating from the association of ZnO rods with rGO.
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paper_title: Microwave-assisted polyol synthesis and characterization of pvp-capped cds nanoparticles for the photocatalytic degradation of tartrazine

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Abstract Polyvinylpyrrolidone capped cadmium sulfide nanoparticles have been successfully synthesized by a facile polyol method with ethylene glycol. Microwave irradiation and calcination were used to control the size and shape of nanoparticles. Characterization with scanning electron microscopy revealed a restricted nanoparticles growth comparing with the uncapped product, hexagonal phase and 48 nm average particle size were confirmed by X-ray diffraction, and finally mechanism of passivation was suggested depending on Fourier transform infrared spectra. The efficiency of nanoparticles was evaluated by the photocatalytic degradation of tartrazine in aqueous solution under UVC and visible light irradiation. Complete degradation of the dye was observed after 90 min of UVC irradiation under optimized conditions. Kinetic of reaction fitted well to the pseudo-first-order kinetic and Langmuir–Hinshelwood models. Furthermore, 85% degradation of the dye in 9 h under visible light suggests that cadmium sulfide is a promising tool to work under visible light for environmental remediation.
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paper_title: Effect of pH on the sonochemical synthesis of BiPO4 nanostructures and its electrochemical properties for pseudocapacitors.

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Using sonochemical method, BiPO4 nanocrystals were prepared at different pH conditions (pH-1, 3, 5, 7, 9 & 12) for the possible applications of pseudocapacitor electrodes. The prepared BiPO4 nanocrystals belong to monoclinic structure with P21 space group. The SEM image revealed that the particles changed from irregular coarse shape into rod like structure (pH-1 to 7) which finally collapsed into irregular aggregates (pH-9 to pH-12). The observed spot patterns from SAED inferred the polycrystalline nature of the material. The electrochemical performance of the synthesized BiPO4 in various ultrasound irradiation conditions such as irradiation time (30min, 1h, 2h and 3h) and ultrasonication power (40%, 50%, 60% and 70% of instrumental power) was studied. A maximum specific capacitance of 1052F/g (pH-7 at 2mV/s) was observed for the BiPO4 prepared in the ultrasonication reaction condition of 2h with 60% power. Also the obtained specific capacitance was high compared with the conventional precipitation method (623F/g at 2mV/s) that revealed the prominence of sonication method. Similarly, BiPO4 prepared at pH-7 delivered a maximum specific capacitance of 302F/g at 2mA/cm(2) calculated from galvanostatic charge-discharge (GCD) method than the other pH conditions. However, the cycling stability of BiPO4 (pH-7) was not appreciable even for 200 cycles. So, attempts were taken to enhance the cycling stability of the material by employing various carbon matrices such as acetylene black, activated carbon and MWCNT instead of carbon black during electrode preparation. BiPO4 material with activated carbon delivered good capacitance retention compared with other carbon matrices. This enhanced electrochemical performance of BiPO4 (pH-7) using activated carbon matrix inferred that it could be utilized as efficient negative electrode material for pseudocapacitors.
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paper_title: Sonochemical synthesis of reduced graphene oxide uniformly decorated with hierarchical ZnS nanospheres and its enhanced photocatalytic activities

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Reduced graphene oxide (rGO) decorated with zinc sulphide nanospheres (ZnSNSs) was synthesized through the simple ultrasonic irradiation of an aqueous solution containing zinc acetate dihydrate (Zn(CH3COO)2·2H2O), thioacetamide (C2H5NS), and graphene oxide (GO). The results of X-ray diffraction, Fourier-transform infrared transmission spectroscopy, X-ray photoelectron spectroscopy and Raman spectroscopy confirmed the simultaneous formation of cubic-phase ZnSNSs and the reduction of GO through the ultrasonic irradiation process. Field emission scanning electron microscope images showed that the size and number density of the nanoparticles could be tuned by adjusting the precursor amounts. Transmission electron microscopy images showed that the spherical ZnS nanoparticles were comprised of small nanoparticles with an average size of ∼5 nm aggregated together. The result of photoluminescence spectroscopy and Brunauer–Emmett–Teller (BET) measurement demonstrated that the incorporation of reduced graphene oxide (rGO) sheets with ZnSNSs suppressed the electron–hole recombination and increased the surface area of the composite. Hence, a significant enhancement in the photocatalytic degradation of methylene blue (MB) was observed with the ZnSNSs–rGO nanocomposite, compared to the bare ZnS particles.
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paper_title: Sonochemical synthesis of Graphene-Ce-TiO 2 and Graphene-Fe-TiO 2 ternary hybrid photocatalyst nanocomposite and its application in degradation of crystal violet dye

paper_content:

Abstract The present work deals with the preparation of graphene oxide (GO) using Hummers-Offeman method in the presence of ultrasonic irradiations. Further loading of TiO2 photocatalyst on prepared GO was accomplished which is basically oxidation reduction reaction between graphene oxide and titanium isopropoxide that leads to the formation of graphene-TiO2 nanocomposite. Graphene-Ce-TiO2 and Graphene-Fe-TiO2 nanocomposites were prepared using one step in-situ ultrasound assisted method using GO, titanium isopropoxide, cerium nitrate, ferric nitrate, and 2-propanol. The successfully prepared graphene-TiO2, Graphene-Ce-TiO2, Graphene-Fe-TiO2 nanocomposites were then characterized using XRD, SEM and TEM analysis. The obtained XRD patterns clearly indicates the formation of anatase TiO2 on graphene nanosheets and it also indicates the presence of Ce and Fe in the Graphene-Ce-TiO2 and Graphene-Fe-TiO2 nanocomposite respectively. Further the use of the prepared nanocomposites as a photocatalyst have been studied for the degradation of crystal violet dye. The effect of various parameters such as catalyst doping, catalyst loading and initial concentration of dye on its degradation were studied. The effectiveness of the prepared catalysts were compared for the degradation of crystal violet dye. It has been observed that Graphene-Fe-TiO2 exhibits maximum photocatalytic activity compared to Graphene-Ce-TiO2 and Graphene-TiO2 nanocomposite photocatalyst.
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paper_title: Facile sonochemical synthesis of N,Cl-codoped TiO2: Synthesis effects, mechanism and photocatalytic performance

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Abstract In this study, both nitrogen and chlorine were successfully doped into TiO 2 (N,Cl-codoped TiO 2 ) via a sonochemical method using titanium(IV) butoxide and ammonium chloride as precursors. When N,Cl-codoped TiO 2 was tested on the decolorization of CI Reactive Black 5 (RB5), it was observed that the photocatalytic activity exhibited by the synthesized photocatalyst was greatly affected by the synthesis conditions. Increasing the sonication intensity or duration up to a certain point shifted the absorption onset toward a lower energy and improved the crystallinity of the synthesized photocatalyst. It was also observed that increasing the N,Cl:Ti molar ratio to 2 significantly enhanced the photocatalytic activity of N,Cl-codoped TiO 2 , but higher molar ratios inhibited the decolorization of RB5. A relatively low calcination temperature of 200 °C was sufficient to further improve the photocatalytic activity of N,Cl-codoped TiO 2 . The following recommended synthesis conditions successfully yielded 96.02% RB5 decolorization under visible light irradiation for 5 h: sonication amplitude of 40%, sonication duration of 3.62 h, N,Cl:Ti molar ratio of 2 and calcination temperature of 200 °C. The decolorization rate constant of N,Cl-codoped TiO 2 (0.01 min −1 ) was also significantly higher than that of commercially available P25 (0.0055 min −1 ).
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paper_title: Sonochemical synthesis of SrMnO 3 nanoparticles as an efficient and new catalyst for O 2 evolution from water splitting reaction

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The principal focus of this investigation is to prepare the SrMnO3 nanostructures by different chemical methods such as ultrasonic, co-precipitation, microwave, and hydrothermal methods. The influence of calcination temperature, and ultrasound irradiation power, and the presence of surfactant investigated on morphology and size of SrMnO3 nanostructures. As-prepared nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray energy dispersive spectroscopy (EDS) and ultraviolet-visible (UV-Vis) spectroscopy. The results indicated that by changing in method and reaction condition, product appeared in different size, morphology, and uniformity. The morphology and size of nanostructures have been influenced on the properties of nano-SrMnO3. For investigation of properties, the SrMnO3 was used in catalytic water splitting for O2 evolution in presence of (NH4)2Ce(NO3)6. The effect of nano-catalysts and the concentration of (NH4)2Ce(NO3)6 have been studied on O2 evolution reaction. Results show that the efficiency of water splitting increased by enhancement in the size and uniformity of catalysts and introduced the SrMnO3 as a new and efficient catalyst for O2 evolution reaction.
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paper_title: One-pot microemulsion-mediated synthesis of Bi-rich Bi4O5Br2 with controllable morphologies and excellent visible-light photocatalytic removal of pollutants

paper_content:

Abstract The novel Bi-rich Bi 4 O 5 Br 2 with tunable morphologies of two-dimentional (2D) nanosheets (NSs), three-dimentional (3D) monodisperse layered microspheres (LMs) and hollow spheres (HSs) have been successfully synthesized via an ionic liquid-in-water (IL/W) microemulsion method. Surfactant TX-100 served as the stabilizer of the IL/W microemulsion, and its concentration significantly influenced the morphology and size of the resulting Bi 4 O 5 Br 2 crystal. Possible formation mechanisms have also been discussed. UV–vis diffuse-reflectance spectra and Density function theory (DFT) calculations indicated that Bi 4 O 5 Br 2 possessed stronger visible light adsorption and more negative conduction band minimum (CBM), which is beneficial to effectively activate molecular oxygen to produce O 2 − . The photocatalytic activity of Bi-rich Bi 4 O 5 Br 2 with varied shapes was investigated and compared with BiOBr for the removal of fungicide o-phenylphenol (OPP) and antibacterial agent norfloxacin (NOR) and tetracycline hydrochloride (TC) under visible light irradiation. The as-prepared Bi 4 O 5 Br 2 HSs and LMs possess higher photocatalytic efficiency than Bi 4 O 5 Br 2 and BiOBr NSs, which is attributed to the hollow/layered spherical structures and Bi-rich strategies. The O 2 − and h + are identified to be the major photoactive species during the photo-degradation process by scavenger experiments and EPR methods. This study is expected to provide a stepping stone to purposively design and explore other novel hollow structures with controllable morphology and enhanced photocatalytic activity.
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paper_title: Methods and strategies for the synthesis of diverse nanoparticles and their applications: a comprehensive overview

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Ongoing advances in nanotechnology research have established a variety of methods to synthesize nanoparticles (NPs) from a diverse range of materials, including metals, semiconductors, ceramics, metal oxides, polymers, etc. Depending upon their origin and synthesis methods, NPs possess unique physicochemical, structural and morphological characteristics, which are important in a wide variety of applications concomitant to electronic, optoelectronic, optical, electrochemical, environment and biomedical fields. This review provides a comprehensive overview on various physical, chemical and bio-assisted methods largely employed to synthesize and fabricate NPs of varying size, surface characteristics, functionalities and physicochemical behavior. The key applications of nanoparticles have also been discussed.
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paper_title: Synthesis of Zn-doped TiO2 nanoparticles by the novel oil-in-water (O/W) microemulsion method and their use for the photocatalytic degradation of phenol

paper_content:

Abstract This investigation is focused on the synthesis of Zn-doped TiO 2 nanomaterials by the O/W microemulsion method and their use for the photodegradation of phenol using a low power UV lamp. TiO 2 nanoparticles with a size smaller than 20 nm and 100% anatase phase were obtained by this method. Thus, the Ti/Zn atomic ratio was varied and the nanomaterials were evaluated in the photodegradation of phenol, which was chosen for the photocatalytic test. The materials presented only the anatase phase upon calcination at 400 °C; phases corresponding to ZnO were not observed by HRTEM or SAED technique, which suggests the formation of Zn-doped TiO 2 . The crystallite size estimated from XRD data were dependent on Zn concentration; the material with the smallest crystallite size was the one with an Ti/Zn atomic ratio of 95/5 (7 nm); the particle size observed by TEM confirm these results. The E g values obtained by diffuse reflectance did not vary significantly, values around 3.2–3.3 eV for the three samples were obtained. The photocatalytic tests showed that the materials are efficient for the degradation of phenol. The most active sample was the Ti/Zn 95/5 mixed oxide, with a phenol mineralization of 82% and 93% degradation after 5 h under irradiation. A mechanism suggesting the presence of tetrahedrally coordinated isolated Ti-oxide is proposed. The obtained results highlight the potential of the O/W microemulsion reaction method for the synthesis of efficient nanostructured photocatalysts such as TiO 2 and Zn-doped TiO 2 for the degradation of emerging pollutants.
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paper_title: One-pot synthesis of BiOCl half-shells using microemulsion droplets as templates with highly photocatalytic performance for the degradation of ciprofloxacin

paper_content:

Ultrathin BiOCl half-shells have been synthesized via an ionic liquid-in-water (IL/W) microemulsion, applying the liquid–liquid boundary of the emulsion system as a template. Surfactant TX-100 acted as the stabilizer of the IL-microemulsion, which is of critical importance for the formation of BiOCl half-shells. The hollow structures were characterized using X-ray diffraction, scanning and transmission electron microscopy, diffuse reflectance spectroscopy and specific surface area, respectively. Possible formation mechanisms for the BiOCl half-shells were discussed. Moreover, the ultrathin BiOCl half-shells exhibited distinctly enhanced photocatalytic efficiency toward the degradation of colourless ciprofloxacin (CIP, a representative broad-spectrum antibiotic agent) under solar light irradiation as compared to BiOCl nanosheets. The photogenerated reactive species are verified by scavenger experiments, which reveals that O2−and h+ were the two major photoactive species toward the photodegradation of CIP over ultrathin BiOCl half-shells under solar-light. The enhanced activities of ultrathin BiOCl half-shells were mainly ascribed to the synergistic effect of the increased light-harvesting, larger BET surface area, faster separation and transfer of electron-hole pairs. It is hoped that the ionic liquid microemulsion-mediated route can be extended to the purposive design and fabrication of other halogen-containing inorganic hollow materials.
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paper_title: Microemulsion synthesis of ZnO–ZnWO4 nanoparticles for superior photodegradation of organic dyes in water

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In the present research, ZnO–ZnWO4 nanocomposite was synthesized by a surfactant assisted microemulsion method. The characteristics of ZnO–ZnWO4 were characterized using various analytical methods. As the amount of ZnWO4 was increased in the composite up to 30 wt%, the particle size decreased. Adding further ZnWO4 resulted in an increase in the grain size. A shift in the energy band gap value from 3.2 to 3.16 eV was observed in the samples by adding 30 wt% ZnWO4. The photocatalytic activity of the prepared nanocatalysts was investigated via photodegradation of methylene blue. The samples obtained from ZnO–30 wt% ZnWO4 heterojunction composite showed the highest activity with 96% photodegradation efficiency.
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paper_title: Formation of carbon nanotubes from polyvinyl alcohol using arc-discharge method

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Abstract The aim of this study is to investigate the possibility of using a polymer material, polyvinyl alcohol (PVA), as an additional carbon source to fabricate carbon nanotubes using arc-discharge method. Experiments were carried out using a graphite anode filled with a mixture of PVA and iron group catalysts. The results indicated that PVA material not only can be used for the formation of carbon nanotubes but also for the formation of some novel carbonaceous structures such as spherical nanoparticles, beaded and sheet-like carbon nanostructures. Furthermore, we found that the catalyst content in the PVA filling mixture should be lower than 50 wt%. In addition, novel catalyst precursors, such as Fe2(SO4)3 · nH2O or Fe(NO3)3 · 9H2O, were employed to grow carbon nanotubes. The results showed that these catalyst precursors can be used to form carbon nanotubes if their filling content does not exceed 50 wt%.
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paper_title: ZnO–TiO 2 nanocomposites formed under submerged DC arc discharge: preparation, characterization and photocatalytic properties

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A rutile TiO2 (α-TiO2) and hexagonal wurtzite ZnO nanocomposite was directly and synchronously synthesized via arc discharge method submerged in de-ionized water. In correlation with the detailed characterization of the morphology, and crystalline structure of the prepared ZnO–TiO2 nanocomposites, the UV–visible and photoluminescence properties were studied. X-ray diffraction and transmission electron microscopy investigations revealed the co-existence of α-TiO2 and hexagonal wurtzite ZnO phases with the ZnO and α-TiO2 nanoparticles are in nanorod and nanospheres morphologies, respectively. The diameters of the synthesized nanocomposite particles are in the range of 5–70 nm. Interestingly, the as-prepared ZnO–TiO2 nanocomposite shows better photocatalytic activity for photodegradation of the methylene blue dye than both of pure ZnO and TiO2 nanocatalyts. This work would explore feasible routes to synthesize efficient metal or/and metal oxide nanocomposites for degrading organic pollutants, gas sensing or other related applications.
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paper_title: ZnO nanoparticles decorated on graphene sheets through liquid arc discharge approach with enhanced photocatalytic performance under visible-light

paper_content:

Abstract We present an innovative approach for synthesis of zinc oxide–graphene (ZnO–G) hybrid nanostructures through combination of improved hummer and arc discharge methods in liquid. A detailed study of the considerable visible-light photocatalytic activities of these nanostructures for the degradation of Phenol red (PR) and Methyl orange (MO) as standard organic compounds under the irradiation of 90 W halogen light for 2 h has been performed. The ZnO–G nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer Emmett Teller (BET) and ultra violet–visible absorption spectroscopy (UV–vis). The results revealed that the ZnO–G nanostructures extended the light absorption spectrum toward the visible region and remarkably enhanced the photodegradation of standard dyes under visible-light irradiation. It has been confirmed that the ZnO–G nanostructures could be excited by visible-light ( E ∼ 2.6 eV). The major enhancement in the photocatalytic activity of ZnO–G nanostructures under visible-light irradiation can be attributed to the effect of electron transport among ZnO nanoparticles (NPs) and graphene sheets. A mechanism for photocatalytic degradation of organic pollutants over ZnO–G photocatalyst was proposed based on our observations.
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paper_title: Nanohybrid of titania/carbon nanotubes – nanohorns: A promising photocatalyst for enhanced hydrogen production under solar irradiation

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Abstract Mixtures of straight and defect-free multiwalled carbon nanotubes (MWCNTs), single walled carbon nanohorns (SWCNHs), and multiwalled carbon nanohorns (MWCNHs) were prepared by the arc discharge method. Functionalized Carbon Nanotubes (FCNTs) composed of MWCNTs, MWCNH S and SWCNHs were obtained using acid functionalization process. TiO 2 /FCNTs (CTP) nanohybrid photocatalysts were obtained with different amounts of FCNTs (2–20 wt%), by wet impregnation method. The photocatalytic activity of both pristine TiO 2 as well as the nanohybrids were studied in aqueous glycerol solution under solar irradiation. Reaction parameters such as amount of catalyst and amount of FCNTs in nanohybrids were optimized to ensure high rates of H 2 production. With a relatively low amount of pristine TiO 2 , a high rate of H 2 production of 2134 μmol h −1 g cat −1 has been obtained and is likely due to several factors such as well dispersed catalyst, reduced particle–particle agglomeration, resulting in enhanced light absorption (less light shielding), improved separation of charge carriers and utilization for red-ox reactions. Even better results were obtained with the use of nanohybrid catalysts. The enhanced photocatalytic activities of the nanohybrid catalysts are ascribed to the synergetic effects of FCNTs that minimize light reflection which promotes enhanced solar light sensitization, good dispersion of the catalysts in the reaction solution, and improved surface-interface reactions of photogenerated charge carriers. In the present study 10 wt% FCNTs in nanohybrid (CTP-10) exhibited superior photocatalytic activity for H 2 generation, nearly 3 times higher than that of pristine TiO 2 catalyst. The CTP-10 photocatalyst exhibited photostability under the experimental conditions studied. The nanohybrid photocatalysts were characterized in order to confirm the crystal structure, morphology, surface chemical composition and optical properties. The present work demonstrates the unique beneficial photocatalytic properties of carbon nanotubes and nanohorn mixtures in nanohybrid photocatalysts, for enhanced H 2 production.
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paper_title: Preparation of Amine-Functionalized TiO2/Carbon Photocatalyst by Arc Discharge in Liquid

paper_content:

Amine-functionalized titanium dioxide/carbon (TiO2/C) was prepared via the arc discharge method using graphite electrodes and a liquid medium consisting of 50% ethanol with the addition of urea. The arc discharge was conducted using a voltage of 20 to 40 V. X-ray diffraction (XRD) of prepared TiO2/C showed a pattern of definitive peaks at 25.32°, 26.61°, and 36.14°, which are the main characteristic peaks of TiO2, C graphite, and titanium carbide, respectively. The successful surface modification of TiO2/C synthesized in liquid ethanol/urea resulted in better dispersion of nanoparticles in water than TiO2/C synthesized in ethanol only. This surface characteristic was also confirmed via Fourier transform infrared (FTIR) spectra of TiO2/C synthesized in liquid ethanol/urea, which revealed C=O, C–N, C–O, and N–H stretching vibrations at 1600–1700, 1400–1100, 1200–1300, and 3300–3400 cm−1, respectively. Scanning electron microscopy (SEM) analysis showed that the nanocomposite had a spherical morphology. Transmission electron microscopy (TEM) analysis found that the structure of the nanocomposite was carbon coated with TiO2.
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paper_title: Effects of electrodeposition synthesis parameters on the photoactivity of nanostructured tungsten trioxide thin films: Optimisation study using response surface methodology

paper_content:

Abstract The main aim of this study was to synthesize and characterise nanostructured tungsten trioxide (WO3) thin films via electrodeposition and subsequently, optimise the electrodeposition synthesis parameters using response surface methodology (RSM). Statistical Box–Behnken RSM design was used to investigate and optimise the effects of four independent electrodeposition synthesis parameters, namely: deposition time, precursor tungsten (W) concentration, annealing temperature and pH. In addition, the synergistic interaction between different electrodeposition synthesis parameters was identified and quantified in enabling a higher photoactivity achievable by nanostructured WO3 thin films. Resultant nanostructured WO3 thin films were characterised using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and photocurrent density measurements under one-Sun irradiation. From the electrodeposition synthesis process, it was found that there was a gradual increase in the nanocrystallites WO3 size from 30 nm to 70 nm when the annealing temperature was varied between 400 °C and 600 °C. XRD results verified the existence of the same photoactive phase of monoclinic WO3 with increasing annealing temperature with the preferred growth orientation along the {002} planar. Whilst from the Box–Behnken RSM design, it was found that the optimum deposition time, precursor W concentration, annealing temperature and pH were: 60 min, 0.15 mol/L, 600 ℃, and pH 1.0, respectively. The highest photocurrent density of 120 µA/cm2 was measured at 1 V (versus Ag/AgCl) for nanostructured WO3 thin film synthesized at the optimum conditions as informed by the Box–Behnken RSM. Further analysis and validation of the Box–Behnken RSM model using analysis of variance (ANOVA) revealed that the RSM-derived statistical predictive model was robust, adequate and representative to correlate the various electrodeposition synthesis parameters to photocurrent density. This study highlights the importance to systematically optimise the electrodeposition synthesis parameters in order to achieve a higher photocurrent density on nanostructured WO3 thin film for sustainable hydrogen production from photoelectrochemical water splitting reaction.
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paper_title: Visible light degradation of textile effluent by electrodeposited multiphase CuInSe2 semiconductor photocatalysts

paper_content:

Abstract Reduction in recombination of photogenerated electron-hole pairs and effective migration of the generated pairs across the surface of the photocatalyst to the aqueous solution of textile effluent can increase the photocatalytic efficiency of a semiconductor. In this study multiphase CuInSe2 (CIS) semiconductor with modified band gap was synthesized through pulsed electrodeposition (PED). Prepared photocatalysts were characterized by XRD, AFM, FESEM, TEM and UV–Vis DRS. The samples exhibited multiphase nature with prominently observed tetragonal and cubic crystallographic structures, having two different modified band gap energy. The photocatalytic degradation efficiency was investigated for the model dyes like methylene blue (MB), Rhodamine B (RhB) dye and the textile effluent under visible light irradiation. Successful degradation of the dyes and textile effluent were attributed to formation of heterojunction of the two phases with two different band gaps, with their energy band edges at the right positions, facilitating efficient migration of the photogenerated charge carriers across the surfaces, before their recombination. It motivates the initiation of chain of redox reactions and degrading reactions with the production of highly reactive hydroxyl radicals which attacked the dyes and the textile effluent. The photocatalytic degradation mechanism was proposed for the electrodeposited photocatalyst.
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paper_title: One-pot electrodeposition synthesis of Bi 2 WO 6 /graphene composites for photocatalytic applications under visible light irradiation

paper_content:

Bi 2 WO 6 and Bi 2 WO 6 /graphene particles were synthesized by electrodeposition. The concentration of graphene in Bi 2 WO 6 /graphene composites was controlled. The impact of graphene concentration on particle morphology and surface area was investigated. The X-ray diffraction patterns indicated the crystal structures of the as-synthesized particles. The photocatalytic performance of both Bi 2 WO 6 and Bi 2 WO 6 /graphene particles was investigated by degrading methylene blue in aqueous solution under visible light irradiation. The results showed that at medium concentration of graphene, the photocatalytic performance was the best, which could be attributed to the increased electron/hole separation during the photocatalysis. A further increased concentration of graphene decreased the photocatalytic performance of Bi 2 WO 6 /graphene, which could be attributed to its prevention of the irradiation reaching the surface of Bi 2 WO 6 .
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paper_title: Electrodeposition synthesis of MnO2/TiO2 nanotube arrays nanocomposites and their visible light photocatalytic activity

paper_content:

MnO2/TiO2 nanotube arrays nanocomposite photocatalysts have been synthesized through an electrodeposition method. X-ray powder diffraction analysis and X-ray photoelectron spectroscopy measurements reveal that the products of electrodeposition method are MnO2. Scanning electron microscopy measurements suggest that the depositions are deposited on the surface or internal of the nanotube. UV-vis light absorbance spectra demonstrate the excellent adsorption properties of MnO 2/TiO2 over the whole region of visible light, which enables this novel photocatalytic material to possess remarkable activity in the photocatalytic degradation of acid Orange II under visible light radiation. Moreover, a possible photocatalytic mechanism is discussed. 2014 Elsevier Ltd.
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paper_title: Highly dispersed phase of SnO2 on TiO2 nanoparticles synthesized by polyol-mediated route: Photocatalytic activity for hydrogen generation

paper_content:

Abstract TiO2–SnO2 mixed oxides (Ti:Sn = 98:2 (TS2), 95:5 (TS5) and 90:10 (TS10) by atomic weight) of large surface area and small particle size, in which SnO2 is in a dispersed phase on TiO2, have been synthesized by a polyol-mediated route. Characterization by various techniques has shown that a highly dispersed phase of SnO2 on anatase TiO2 is formed in TS2 sample. No separate discernible phases corresponding to cassiterite SnO2 or rutile TiO2 is seen in TS2 sample, whereas rutile TiO2 and SnO2 are observed besides the anatase phase of TiO2 in TS5 and TS10 samples. The average particle size of the mixed oxide samples is ∼20 nm. All samples absorb visible light and the onset of absorption was ∼425 nm. These mixed oxides show emission from defect levels arising due to the anion vacancies present in TiO2. The visible light absorption of these samples is attributed to the presence of defect levels in the bandgap of TiO2. Photocatalytic activity of these samples for hydrogen generation from water using methanol as sacrificial reagent was studied under sunlight type radiation. The results indicate that mixed oxides have better activity compared to pure TiO2 synthesized by the same method and the activity decreases with increasing SnO2 concentration in TiO2. The enhanced activity of TS2 sample is ascribed to the efficient charge separation from TiO2 to SnO2 owing to the high dispersion of SnO2 in TiO2. The decreased photocatalytic activity with increased SnO2 concentration is due to the aggregation of SnO2 on TiO2, which results in relatively poor dispersion of SnO2 and decreased charge transfer efficiency, but still maintains better photocatalytic activity compared to TiO2. In addition loading Pd co-catalyst produces a pronounced increase in the hydrogen yield due to the accumulation of electrons in the metal from the TiO2 and SnO2 semiconductors and the increased reductive power of the Pd loaded mixed oxide nanoparticles.
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paper_title: Microwave-assisted polyol synthesis and characterization of pvp-capped cds nanoparticles for the photocatalytic degradation of tartrazine

paper_content:

Abstract Polyvinylpyrrolidone capped cadmium sulfide nanoparticles have been successfully synthesized by a facile polyol method with ethylene glycol. Microwave irradiation and calcination were used to control the size and shape of nanoparticles. Characterization with scanning electron microscopy revealed a restricted nanoparticles growth comparing with the uncapped product, hexagonal phase and 48 nm average particle size were confirmed by X-ray diffraction, and finally mechanism of passivation was suggested depending on Fourier transform infrared spectra. The efficiency of nanoparticles was evaluated by the photocatalytic degradation of tartrazine in aqueous solution under UVC and visible light irradiation. Complete degradation of the dye was observed after 90 min of UVC irradiation under optimized conditions. Kinetic of reaction fitted well to the pseudo-first-order kinetic and Langmuir–Hinshelwood models. Furthermore, 85% degradation of the dye in 9 h under visible light suggests that cadmium sulfide is a promising tool to work under visible light for environmental remediation.
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paper_title: Self-assembled Cu2O flowerlike architecture: Polyol synthesis, photocatalytic activity and stability under simulated solar light

paper_content:

National Natural Science Foundation of China [20973070, 50804035]; National Key Basic Research Program of China [2009CB939704]; Key Project of Chinese Ministry of Education [109116]; Natural Science Foundation of Hubei Province, China [2009CDB004]; Progra
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paper_title: Polyol Synthesis of Size-Controlled Rh Nanoparticles and Their Application to Photocatalytic Overall Water Splitting under Visible Light

paper_content:

A gradual size control of poly(N-vinyl-2-pyrrolidone)-protected Rh nanoparticles (PVP-Rh NPs) was successfully achieved in the range of 1.7–7.7 nm by tuning the pH value and the reaction temperature of the ethylene glycol (EG) solution; smaller NPs were formed at higher pH and at higher temperature. This trend can be interpreted by the change in the nucleation rate caused by tuning the pH value and/or the temperature of the solution. When the size tuned PVP-Rh NPs were applied for use as cocatalysts in a photocatalyst (solid solution of GaN and ZnO (Ga1–xZnx)(N1–xOx)) for overall water splitting under visible light, it was demonstrated that smaller Rh cores gave higher activity than the larger ones.
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paper_title: Effects of pH on Tin Nanoparticles Prepared Using a Modified Polyol Synthesis

paper_content:

The effects of pH on the morphology and size distribution of Sn nanoparticles (NPs)synthesized using a modified polyol method were investigated. An ammonia solution wasused to increase the pH, and at pHvalues ranging from 10.3 to 12, the average size and size deviation of thesynthesized Sn NPs decreased with increasing pH. We believe that higherpH enhances the rate of reduction of Sn ions during the synthesis, resulting inan increase in nucleation. Therefore, theconcurrent formation of many nuclei might be the main cause for the reduction inaverage particle size and for the enhancement in size uniformity.
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paper_title: Facile polyol synthesis of CuS nanocrystals with a hierarchical nanoplate structure and their application for electrocatalysis and photocatalysis

paper_content:

The article describes a robust method for the facile polyol synthesis of high-quality CuS nanocrystals with a controlled hierarchical nanoplate structure. The success of this method relies on manipulating the reaction kinetics with different sulfur precursors. In particular, with a medium releasing rate of S2−, we are able to produce CdS hierarchical spherical nanoflowers composed with multi-layered nanoplates, while a slow or fast release of S2− gives the monodispersed hexagonal nanoplates or disordered nanoplate complexes, respectively. Benefitting from its large surface area and the hierarchical structure for light reflection, the CuS nanoflower with a hierarchical plate structure showed the best electrocatalytic and photocatalytic performances when benchmarking its activity with the well-shaped nanoplate and the disordered nanoplate complex.
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paper_title: Efficient synthesis of monolayer carbon nitride 2D nanosheet with tunable concentration and enhanced visible-light photocatalytic activities

paper_content:

Abstract A versatile and scalable mixed solvent strategy was developed to prepare monolayer C3N4 nanosheets with tunable concentration for the first time. This approach could also be used to prepare other 2D nanosheets from their layered materials (such as MoS2, BN, WS2 etc.). The structural features and intrinsic semiconductor properties of the as-prepared C3N4 nanosheets have been investigated in detailed. The photocatalytic activities were evaluated by photocatalytic oxidation of both benzyl alcohol and rhodamine B (RhB) under visible light irradiation. Results showed that the as-prepared monolayer C3N4 nanosheets with thickness of 0.4 nm still retained the structural features of g-C3N4 layer. The functionalities of C3N4 nanosheets well inherited from the layered parent counterpart. Furthermore, due to the exceptionally high 2D anisotropy, C3N4 nanosheets showed the distinctive physicochemical properties and unique electronic structures, such as high surface area, lower surface defects, stronger reduction ability of the photogenerated electrons, increased photoelectric response, and promoted the charge-carrier migration and separation. All of these favorable factors co-contributed to the greatly improved photocatalytic activities over C3N4 nanosheets compared with those of its bulk counterpart.
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paper_title: Efficient solar water-splitting using a nanocrystalline CoO photocatalyst.

paper_content:

The generation of hydrogen from water using sunlight could potentially form the basis of a clean and renewable source of energy. Various water-splitting methods have been investigated previously, but the use of photocatalysts to split water into stoichiometric amounts of H2 and O2 (overall water splitting) without the use of external bias or sacrificial reagents is of particular interest because of its simplicity and potential low cost of operation. However, despite progress in the past decade, semiconductor water-splitting photocatalysts (such as (Ga1-xZnx)(N1-xOx)) do not exhibit good activity beyond 440 nm (refs 1,2,9) and water-splitting devices that can harvest visible light typically have a low solar-to-hydrogen efﬁciency of around 0.1%. Here we show that cobalt(II) oxide (CoO) nanoparticles can carry out overall water splitting with a solar-to-hydrogen efficiency of around 5%. The photocatalysts were synthesized from non-active CoO micropowders using two distinct methods (femtosecond laser ablation and mechanical ball milling), and the CoO nanoparticles that result can decompose pure water under visible-light irradiation without any co-catalysts or sacrificial reagents. Using electrochemical impedance spectroscopy, we show that the high photocatalytic activity of the nanoparticles arises from a significant shift in the position of the band edge of the material.
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paper_title: Band gap-engineered ZnO and Ag/ZnO by ball-milling method and their photocatalytic and Fenton-like photocatalytic activities

paper_content:

Abstract The hybridization of ZnO with Ag has been performed extensively to increase the efficiency of ZnO in various applications, including catalysis. In this study, a wet (w) and dry (d) ball-milling method was used to hybridize Ag with ZnO nanoparticles, and their physicochemical properties were examined. Visible light absorption was enhanced and the band gap was engineered by ball-milling and Ag hybridization. Their photocatalytic activities were tested with rhodamine B (RhB) and a mixed dye (methyl orange + RhB + methylene blue) under visible light irradiation. For pure RhB, the photocatalytic activity was decreased by ball-milling and was observed in the order of ZnO(d) 2 O 2 addition, however, the Fenton-like photocatalytic activity was reversed and the ZnO(ref) showed the poorest activity for the degradation of RhB and methylene blue (MB). In the mixed dye over all the catalysts, methyl orange (MO) was degraded most rapidly. The relative degradation rates of RhB and MB were found to be dependent on the catalyst and reaction conditions.
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paper_title: High Energy Ball-Milling Synthesis of Nanostructured Ag-Doped and BiVO4-Based Photocatalysts

paper_content:

Nanostructured composites based on plasmonic Ag metal nanoclusters with monoclinc-BiVO4 nanoparticles were prepared by high energy ball milling technique. The agglomerated morphology with a spherical shape of 50–100 nm sized BiVO4 particles associated with homogeneous distribution of 5–10 nm Ag clusters significantly enhanced the photocatalytic activity for the degradation of acid blue dyes. The Ag doping concentration with BiVO4 was optimized at 3 at. % leading to almost 10 folds faster photocatalytic degradation rate as compared to pristine form. Thus, Ag doped BiVO4 nanocomposites show efficient visible light driven photocatalytic activity due to charge distribution at the semiconducting-metal interfaces from band bending and the involvement of a radiation field enhanced by plasmon resonance effects at the surfaces of Ag-clusters.
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paper_title: MoS2 quantum dots@TiO2 nanotube composites with enhanced photoexcited charge separation and high-efficiency visible-light driven photocatalysis

paper_content:

MoS2 quantum dots (QDs) that are 5 nm in size were deposited on the surface of ultrathin TiO2 nanotubes (TNTs) with 5 nm wall thickness by using an improved hydrothermal method to form a MoS2 QDs@TNT visible-light photocatalyst. The ultrathin TNTs with high percentage of photocatalytic reactive facets were fabricated by the commercially available TiO2 nanoparticles (P25) through an improved hydrothermal method, and the MoS2 QDs were acquired by using a surfactant-assisted technique. The novel MoS2 QDs@TNT photocatalysts showed excellent photocatalytic activity with a decolorization rate of 92% or approximately 3.5 times more than that of pure TNTs for the high initial concentration of methylene blue solution (20 mg l−1) within 40 min under visible-light irradiation. MoS2 as the co-catalysts favored the broadening of TNTs into the visible-light absorption scope. The quantum confinement and edge effects of the MoS2 QDs and the heterojunction formed between the MoS2 QDs and TNTs efficiently extended the lifetime of photoinduced charges, impeded the recombination of photoexcited electron–hole pairs, and improved the visible-light-driven high-efficiency photocatalysis.
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paper_title: A simple and convenient fluorescent strategy for the highly sensitive detection of dopamine and ascorbic acid based on graphene quantum dots

paper_content:

Abstract In this paper, a simple and convenient fluorescent “turn off-on” strategy for the highly sensitive detection of dopamine (DA) and ascorbic acid (AA) based on graphene quantum dots (GQDs) was developed. DA and GQDs can form the DA-GQDs complex due to the electrostatic interaction and hydrogen bonding. The interaction between Cu2+ and the catechol moiety of DA-GQDs complex could lead to strong fluorescence quenching of GQDs. When AA is introduced into the system, AA can reduce Cu2+ to Cu+, disturbing the interaction between Cu2+ and DA-GQDs complex and resulting in the fluorescence recovery of GQDs. Thus, a sensitive and convenient sensor for the detection of DA and AA was developed. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of DA and AA in the range of 0.5–120 µmol L−1 and 0.05–6 µmol L−1 with a detection limit of 0.16 µmol L−1 and 0.021 µmol L−1, respectively. Meanwhile, the proposed method has potential applications on the detection of DA and AA in human urine and serum samples.
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paper_title: Characterization of thin TiO2 films prepared by plasma enhanced chemical vapour deposition for optical and photocatalytic applications

paper_content:

Abstract Thin titanium oxide films were deposited using a radio frequency (RF) plasma enhanced chemical vapour deposition method. Their optical properties and thickness were determined by means of ultraviolet–visible absorption spectrophotometry. Films of the optical parameters very close to those of titanium dioxide have been obtained at the high RF power input. Their optical quality is high enough to allow for their use in a construction of stack interference optical filters. At the same time, these materials exhibit strong photocatalytic effects. The results of structural analysis, carried out by Raman Shift Spectroscopy, show that the coatings posses amorphous structure. However, Raman spectra of the same films subjected to thermal annealing at 450 °C disclose an appearance of a crystalline form, namely that of anatase. Surface morphology of the films has also been characterized by Atomic Force Microscopy revealing granular, broccoli-like topography of the films.
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paper_title: Synthesis and Microstructural Characterization of SnO2:F Thin Films Deposited by AACVD

paper_content:

In this work, we report the synthesis and microstructural characterization of Tin oxide thin films doped with fluorine for applications such as transparent conductive oxides. Tin oxide doped with fluorine thin films were deposited by aerosol assisted chemical vapor deposition technique onto a borosilicate glass substrate, using a precursor solution of stannic chloride in ethanol and ammonium fluoride as the dopant. Deposition temperature was varied between 623-773 K. Also, other deposition parameters such as concentration of the precursor solution and gas carrier flux were fixed at 0.1 mol∙dm-3 and 5 L min-1 respectively. Results indicate the presence of only the cassiterite phase of Tin oxide in all samples. Thin films obtained were characterized by X-Ray Diffraction. Surface morphology and microstructure were studied by field emission scanning electron microscopy, optical properties of samples were analyzed by total transmittance and reflectance spectra. The resistivity value of the films was measured by the sheet resistance.
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paper_title: Novel continuous single-step synthesis of nitrogen-modified TiO 2 by flame spray pyrolysis for photocatalytic degradation of phenol in visible light

paper_content:

Abstract A novel rapid and continuous process has developed for the synthesis of nitrogen-doped TiO2 (N-TiO2) with flame spray pyrolysis (FSP) method. The nitrogen incorporation into TiO2 was achieved by a facile modification (addition of dilute nitric acid) in the precursor for the synthesis. The catalysts were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. The doping of nitrogen into the TiO2 was confirmed by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray (EDX) spectroscopy. The UV–vis spectra of the modified catalysts (with primary N source) exhibited band-gap narrowing for 4N-TiO2 with band gap energy of 2.89 eV, which may be due to the presence of nitrogen in TiO2 structure. The introduction of secondary N-source (urea) into TiO2 crystal lattice results in additional reduction of the band gap energy to 2.68 eV and shows a significant improvement of visible light absorption. The N-TiO2 nanoparticles modified by using secondary N-source showed significant photocatalytic activity under visible light much higher than TiO2. The higher activity is attributed to the synergetic interaction of nitrogen with the TiO2 lattice. The lowering of the band-gap energy for the flame made N-doped TiO2 materials implies that the nitrogen doping in TiO2 by aerosol method is highly effective in extending the optical response of TiO2 in the visible region. The nitrogen atomic percentage has increased monotonically (0.09%–0.15%) with the increase in primary nitrogen source (nitric acid), and significantly boosted to 0.97% when secondary nitrogen source (urea) was introduced. The highest rate of phenol degradation was obtained for catalysts with secondary N source due to increase in N content in the catalyst.
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paper_title: Symbiotic Interaction of Amalgamated Photocatalysts with Improved Day Light Utilisation and Charge Separation

paper_content:

A promising amalgamation of organic with inorganic semiconductor photocatalyst (g-C3N4/SrTiO3) with varied g-C3N4 concentration was synthesised through a simple thermal method. The organic semiconductor was prepared through a facile pyrolysis of urea while perovskite (SrTiO3) by sol-gel hydrothermal route. The observed mechanistic characteristics of the synthesised composite photocatalysts were thoroughly analysed through robust analytical tools. The dissection analysis clearly revealed that amalgamation of organic semiconductor stimulated the utilisation of solar spectrum by enhancing the light absorption towards visible band. Where else perovskite activated close interfacial connections leading to enhanced efficiency of electron migration. The Electron Paramagnetic Resonance (EPR) excited under solar spectrum along with Photoluminescence (PL) clearly indicated the prolongation of the charge carriers. A symbiotic interaction with mutual benefit was clearly observed between these photocatalysts. The solar photocatalysis ability of the perovskite composite was examined by degrading a non-photosensitising compound (Bisphenol A). The photocatalysis experiment clearly revealed its dominant solar light harvesting capability of the developed perovskite amalgamated organic photocatalyst.
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paper_title: Combinatorial aerosol assisted chemical vapour deposition of a photocatalytic mixed SnO2/TiO2 thin film

paper_content:

Combinatorial Aerosol Assisted Chemical Vapour Deposition (cAACVD) was used to grow a thin film that graduated across its width from tin dioxide to titanium dioxide. This is a relatively new technique that can be used to create a variety of mixed phase and composition thin films on a single substrate. Here cAACVD was used to deposit a mixed phase TiO2 and SnO2 film and composition was related to UV photocatalysis, hydrophobicity and microstructure not inherent to anatase TiO2 or cassiterite SnO2. Characterisation was achieved using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and UV-Vis spectroscopy. Functional testing to elucidate the differences in functional properties across the film was undertaken by the photo-induced degradation of a resazurin ‘intelligent’ ink, a photo-induced wettability study and two-point resistivity measurements. Functional properties showed enhanced photocatalysis in comparison to Pilkington Activ™ with similar formal quantum yield (molecules destroyed per absorbed photon) and formal quantum efficiency (molecules destroyed per incident photon) values.
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paper_title: Effects of electrodeposition synthesis parameters on the photoactivity of nanostructured tungsten trioxide thin films: Optimisation study using response surface methodology

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Abstract The main aim of this study was to synthesize and characterise nanostructured tungsten trioxide (WO3) thin films via electrodeposition and subsequently, optimise the electrodeposition synthesis parameters using response surface methodology (RSM). Statistical Box–Behnken RSM design was used to investigate and optimise the effects of four independent electrodeposition synthesis parameters, namely: deposition time, precursor tungsten (W) concentration, annealing temperature and pH. In addition, the synergistic interaction between different electrodeposition synthesis parameters was identified and quantified in enabling a higher photoactivity achievable by nanostructured WO3 thin films. Resultant nanostructured WO3 thin films were characterised using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and photocurrent density measurements under one-Sun irradiation. From the electrodeposition synthesis process, it was found that there was a gradual increase in the nanocrystallites WO3 size from 30 nm to 70 nm when the annealing temperature was varied between 400 °C and 600 °C. XRD results verified the existence of the same photoactive phase of monoclinic WO3 with increasing annealing temperature with the preferred growth orientation along the {002} planar. Whilst from the Box–Behnken RSM design, it was found that the optimum deposition time, precursor W concentration, annealing temperature and pH were: 60 min, 0.15 mol/L, 600 ℃, and pH 1.0, respectively. The highest photocurrent density of 120 µA/cm2 was measured at 1 V (versus Ag/AgCl) for nanostructured WO3 thin film synthesized at the optimum conditions as informed by the Box–Behnken RSM. Further analysis and validation of the Box–Behnken RSM model using analysis of variance (ANOVA) revealed that the RSM-derived statistical predictive model was robust, adequate and representative to correlate the various electrodeposition synthesis parameters to photocurrent density. This study highlights the importance to systematically optimise the electrodeposition synthesis parameters in order to achieve a higher photocurrent density on nanostructured WO3 thin film for sustainable hydrogen production from photoelectrochemical water splitting reaction.
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paper_title: Efficient synthesis of monolayer carbon nitride 2D nanosheet with tunable concentration and enhanced visible-light photocatalytic activities

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Abstract A versatile and scalable mixed solvent strategy was developed to prepare monolayer C3N4 nanosheets with tunable concentration for the first time. This approach could also be used to prepare other 2D nanosheets from their layered materials (such as MoS2, BN, WS2 etc.). The structural features and intrinsic semiconductor properties of the as-prepared C3N4 nanosheets have been investigated in detailed. The photocatalytic activities were evaluated by photocatalytic oxidation of both benzyl alcohol and rhodamine B (RhB) under visible light irradiation. Results showed that the as-prepared monolayer C3N4 nanosheets with thickness of 0.4 nm still retained the structural features of g-C3N4 layer. The functionalities of C3N4 nanosheets well inherited from the layered parent counterpart. Furthermore, due to the exceptionally high 2D anisotropy, C3N4 nanosheets showed the distinctive physicochemical properties and unique electronic structures, such as high surface area, lower surface defects, stronger reduction ability of the photogenerated electrons, increased photoelectric response, and promoted the charge-carrier migration and separation. All of these favorable factors co-contributed to the greatly improved photocatalytic activities over C3N4 nanosheets compared with those of its bulk counterpart.
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paper_title: An efficient TiO2 thin-film photocatalyst : photocatalytic properties in gas-phase acetaldehyde degradation

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Abstract A semitransparent TiO 2 film with extraordinarily high photocatalytic activity was prepared on a glass substrate by sintering a TiO 2 sol at 450 °C. Crystallographic analysis by X-ray diffraction and Raman spectroscopy showed that the film was purely anatase. The photocatalytic properties of the film were investigated by measuring the photodegradative oxidation of gaseous acetaldehyde at various concentrations under strong and weak UV light irradiation conditions. The photocatalytic activity of the film was higher than that of one of the most active commercial TiO 2 powders, Degussa P-25. The kinetics of acetaldehyde degradation as catalyzed by the TiO 2 film as well as by P-25 powder were analyzed in terms of the Langmuir-Hinshelwood model. It is shown that the number of adsorption sites per unit true surface area is larger with the TiO 2 film, as analyzed in the powder form, than with P-25 powder. Meanwhile, the first-order reaction rate constant is also much larger with the film than with P-25 powder. Moreover, under most experimental conditions, particularly with high concentrations of acetaldehyde and weak UV illumination intensity, the quantum efficiency was found to exceed 100% on an absorbed-photon basis, assuming that only photo-generated holes play a major role in the reaction. This leads to the conclusion that the photodegradative oxidation of acetaldehyde is not mediated solely by hydroxyl radicals, generated via hole capture by surface hydroxyl ions or water molecules, but also by photocatalytically generated superoxide ion, which can be generated by the reduction of adsorbed oxygen with photogenerated electrons.
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paper_title: Highly Transparent Wafer-Scale Synthesis of Crystalline WS2 Nanoparticle Thin Film for Photodetector and Humidity-Sensing Applications.

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In the present investigation, we report a one-step synthesis method of wafer-scale highly crystalline tungsten disulfide (WS2) nanoparticle thin film by using a modified hot wire chemical vapor deposition (HW-CVD) technique. The average size of WS2 nanoparticle is found to be 25–40 nm over an entire 4 in. wafer of quartz substrate. The low-angle XRD data of WS2 nanoparticle shows the highly crystalline nature of sample along with orientation (002) direction. Furthermore, Raman spectroscopy shows two prominent phonon vibration modes of E12g and A1g at ∼356 and ∼420 cm–1, respectively, indicating high purity of material. The TEM analysis shows good crystalline quality of sample. The synthesized WS2 nanoparticle thin film based device shows good response to humidity and good photosensitivity along with good long-term stability of the device. It was found that the resistance of the films decreases with increasing relative humidity (RH). The maximum humidity sensitivity of 469% along with response time of ∼12 ...
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paper_title: Novel one-step synthesis of sulfur doped-TiO2 by flame spray pyrolysis for visible light photocatalytic degradation of acetaldehyde

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Abstract Novel one-step synthesis route for S-doped TiO 2 photocatalysts by flame spray pyrolysis (FSP) for visible light photocatalysis was developed. We observed improved visible light absorption and reduction of the band gap energies to 2.78 eV. Addition of sulfur in the TiO 2 promoted the anatase to rutile transformation in the prepared catalysts. The S oxidation states along with optical properties of the catalyst were studied using X-ray photoelectron spectroscopy (XPS) and UV–Vis spectroscopy. The oxidation state of the S atoms incorporated into the TiO 2 is determined to be mainly S 4+ and S 6+ in the XPS spectra. Among all the synthesized catalysts, catalyst with 2 M sulfuric acid in precursor illustrated an impressive performance for the visible light induced photocatalysis along with higher S 6+ /S 4+ of 5.61. The S +6 presence has important role in enhancing the visible light photocatalytic activity. The photocatalytic activity of the sulfur-doped TiO 2 was evaluated through the degradation of acetaldehyde under visible light irradiation. Our results show that we developed a new synthesis method to achieve stable and highly efficient solar light-driven S-modified TiO 2 photocatalysts for water purification.
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paper_title: Aerosol assisted chemical vapour deposition of a ZrO2–TiO2 composite thin film with enhanced photocatalytic activity

paper_content:

ZrO2–TiO2 composite thin films were deposited by aerosol assisted chemical vapour deposition onto a glass substrate at 450 °C and then annealed at 600 °C. For comparison ZrO2 thin films and TiO2 thin films were deposited under the same conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), UV-Vis and Raman spectroscopy were used to characterize all films. Photocatalytic activities were tested by degradation of intelligent ink containing resazurin redox dye under UVA irradiation. The formal quantum efficiency (FQE) and yield (FQY) for the ZrO2–TiO2 composite thin films were determined as 2.03 × 10−3 dye molecules per incident photon and 4.91 × 10−3 dye molecules per absorbed photon respectively. Surprisingly the ZrO2–TiO2 composite was a more efficient photocatalyst than the comparable TiO2 coating.
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paper_title: A Nonmetal Plasmonic Z-Scheme Photocatalyst with UV- to NIR-Driven Photocatalytic Protons Reduction

paper_content:

Ultrabroad-spectrum absorption and highly efficient generation of available charge carriers are two essential requirements for promising semiconductor-based photocatalysts, towards achieving the ultimate goal of solar-to-fuel conversion. Here, a fascinating nonmetal plasmonic Z-scheme photocatalyst with the W18O49/g-C3N4 heterostructure is reported, which can effectively harvest photon energies spanning from the UV to the nearinfrared region and simultaneously possesses improved charge-carrier dynamics to boost the generation of long-lived active electrons for the photocatalytic reduction of protons into H2. By combining with theoretical simulations, a unique synergistic photocatalysis effect between the semiconductive Z-scheme charge-carrier separation and metal-like localized-surface-plasmon-resonance-induced “hot electrons” injection process is demonstrated within this binary heterostructure.
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paper_title: A new supported TiO2 film deposited on stainless steel for the photocatalytic degradation of contaminants of emerging concern

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Abstract A new supported catalyst composed of a nanostructured TiO 2 film deposited on a stainless steel mesh (nanoTiO 2 -SS) using the Metal Organic Chemical Vapour Deposition (MOCVD) technique was evaluated for the photocatalytic degradation of a mixture of contaminants of emerging concern. Results showed that under the oxidative conditions tested, the nanoTiO 2 -SS catalyst demonstrated an efficiency in degrading the target contaminants higher than that observed under direct photolysis and photocatalysis using the conventional TiO 2 Degussa P25 catalyst at the same amount of TiO 2 participating to the photocatalysis. Specifically, the rate of removal of warfarin and trimethoprim obtained with the new catalyst was found twice the one observed by using TiO 2 Degussa P25 and approximately 1.6 times faster for metoprolol, carbamazepine and gemfibrozil. An evaluation of the electrical energy per order magnitude of removal (EE/O) confirmed the enhanced performance of the new catalyst (24.3–31.8 kWh m −3 rather than 32.8–39.3 kWh m −3 for conventional TiO 2 ) and that the performance is compound-dependent. Toxicity testing revealed that some assays are suitable for the investigation of bioactivity of treated waters containing contaminants of emerging concern at μg L −1 level. Specifically, the AMES Fluctuation Test, Fish Embryo Acute Toxicity Test and Green alga Selenastrum capricornutum test provided valuable results for an environmental impact assessment. On the other hand, the Daphnia magna and Vibrio fischeri acute toxicity tests were not sensitive enough to detect bioactivity in the samples analysed without prior pre-concentration.
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paper_title: Photocatalytic performance of Sn-doped and undoped TiO2 nanostructured thin films under UV and vis-lights

paper_content:

Abstract Sn-doped and undoped nano-TiO 2 particles have been synthesized by hydrotermal process without solvent at 200 °C in 1 h. Nanostructure-TiO 2 based thin films have been prepared on glass substrate by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, SEM, BET and UV–vis–NIR techniques. The photocatalytic performance of the films were tested for degradation of Malachite Green dye in solution under UV and vis-lights. The results showed that (a) hydrothermally synthesized nano-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water, (b) the coated surfaces have nearly super-hydrophilic properties and, (c) the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO 2 thin film.
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paper_title: Facile sonochemical synthesis of N,Cl-codoped TiO2: Synthesis effects, mechanism and photocatalytic performance

paper_content:

Abstract In this study, both nitrogen and chlorine were successfully doped into TiO 2 (N,Cl-codoped TiO 2 ) via a sonochemical method using titanium(IV) butoxide and ammonium chloride as precursors. When N,Cl-codoped TiO 2 was tested on the decolorization of CI Reactive Black 5 (RB5), it was observed that the photocatalytic activity exhibited by the synthesized photocatalyst was greatly affected by the synthesis conditions. Increasing the sonication intensity or duration up to a certain point shifted the absorption onset toward a lower energy and improved the crystallinity of the synthesized photocatalyst. It was also observed that increasing the N,Cl:Ti molar ratio to 2 significantly enhanced the photocatalytic activity of N,Cl-codoped TiO 2 , but higher molar ratios inhibited the decolorization of RB5. A relatively low calcination temperature of 200 °C was sufficient to further improve the photocatalytic activity of N,Cl-codoped TiO 2 . The following recommended synthesis conditions successfully yielded 96.02% RB5 decolorization under visible light irradiation for 5 h: sonication amplitude of 40%, sonication duration of 3.62 h, N,Cl:Ti molar ratio of 2 and calcination temperature of 200 °C. The decolorization rate constant of N,Cl-codoped TiO 2 (0.01 min −1 ) was also significantly higher than that of commercially available P25 (0.0055 min −1 ).
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paper_title: One step synthesis of N-doped and Au-loaded TiO2 nanoparticles by laser pyrolysis: Application in photocatalysis

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Photocatalysis is a major tool for air and water depollution and photocatalysts with improved efficiency in the visible range are still needed. In this context, we show that N-TiO2 nanoparticles modified with Au, called Au/N-TiO2, seem to represent a good compromise: significant photocatalytic activity is observed under visible light together with an activity higher than TiO2 P25 under UV irradiation. In order to demonstrate such efficiency of the Au/N-TiO2 sample, TiO2, Au-TiO2, N-TiO2 and Au modified N-TiO2 nanoparticles were synthesized in one step using the laser pyrolysis method. The photocatalytic activity of the powders was evaluated through the photocatalytic degradation of formic acid (FA) both under UV and visible light irradiation. Under UV irradiation, all the laser-synthesized samples exhibit a high efficiency compared to commercial TiO2 P25. Moreover, the modification by Au induces an enhancement of the photocatalytic activity compared to pure TiO2 even at very low concentrations. Under visible light, the N-doped samples exhibit some photoactivity and the degradation rate of FA in presence of Au/N-TiO2 is much increased compared to N-TiO2. In conclusion, our Au/N-TiO2 sample exhibits efficiency better than P25 under UV together with an activity under visible light.
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paper_title: Hierarchical synthesis of non-centrosymmetric hybrid nanostructures and enabled plasmon-driven photocatalysis

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Non-centrosymmetric nanostructures consisting of multiple functional subunits represents an emerging class of hybrid nanostructures that can possess dramatic difference in property and functionality from concentric core-shell configuration. Here we develop a general synthetic method to achieve hierarchical control of high-order non-centrosymmetric hybrid nanostructures. The key is to employ a common intermedium for sequential conversion to all distinct predesigned subunits under similar growth condition, thus facilitating manifold control of a hybrid nanostructure. This advancement leads to an optimally designed plasmon-mediated photocatalytic nanostructure with 14.8-fold enhancement of photocatalytic efficiency as compared with conventional photocatalysts. Mechanistic study involving theoretical modelling and ultrafast time-resolved optical measurement uncovers a hot plasmonic electron-driven photocatalysis mechanism with an identified electron transfer pathway. This study may represent an important step towards high-level control of artificial nanostructures with new horizons for fundamental and technological applications.
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paper_title: Defect-Mediated Growth of Noble-Metal (Ag, Pt, and Pd) Nanoparticles on TiO2 with Oxygen Vacancies for Photocatalytic Redox Reactions under Visible Light

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A synergistic strategy involving oxygen-vacancy generation and noble-metal deposition is developed to improve the photocatalytic performance of TiO2 under visible-light irradiation. Through a redox reaction between the reductive TiO2 with oxygen vacancies (TiO2-OV) and metal salt precursors, noble-metal nanoparticles (Ag, Pt, and Pd) are uniformly deposited on the defective TiO2-OV surface in the absence of any reducing agents or stabilizing ligands. The resulting M-TiO2-OV (M = Ag, Pt, and Pd) nanocomposites are used as visible-light-driven photocatalysts for selective oxidation of benzyl alcohol and reduction of heavy metal ions Cr(VI). The results show that the oxygen vacancy creation obviously enhances the visible-light absorption of semiconductor TiO2. Meanwhile, the noble-metal deposition can effectively improve charge-separation efficiency of TiO2-OV under visible-light irradiation, thereby enhancing the photoactivity. In particular, Pd-TiO2-OV, having the average Pd particle size of 2 nm, shows th...
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paper_title: Embedded structure catalyst: a new perspective from noble metal supported on molybdenum carbide

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An embedded structure of noble metal (Pt) in situ supported on molybdenum carbide was found for the first time, which hindered Pt sintering at high temperature, and promoted the interaction between Pt and molybdenum carbide. This structure exhibited an excellent and stable catalytic activity for water gas shift reaction at low temperature.
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paper_title: Mechanistic insights into plasmonic photocatalysts in utilizing visible light

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The utilisation of sunlight as an abundant and renewable resource has motivated the development of sustainable photocatalysts that can collectively harvest visible light. However, the bottleneck in utilising the low energy photons has led to the discovery of plasmonic photocatalysts. The presence of noble metal on the plasmonic photocatalyst enables the harvesting of visible light through the unique characteristic features of the noble metal nanomaterials. Moreover, the formation of interfaces between noble metal particles and semiconductor materials further results in the formation of a Schottky junction. Thereby, the plasmonic characteristics have opened up a new direction in promoting an alternative path that can be of value to the society through sustainable development derived through energy available for all for diverse applications. We have comprehensively prepared this review to specifically focus on fundamental insights into plasmonic photocatalysts, various synthesis routes, together with their strengths and weaknesses, and the interaction of the plasmonic photocatalyst with pollutants as well as the role of active radical generation and identification. The review ends with a pinnacle insight into future perspectives regarding realistic applications of plasmonic photocatalysts.
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paper_title: Catalysis with TiO2/gold nanocomposites. Effect of metal particle size on the Fermi level equilibration.

paper_content:

Photoexcited semiconductor nanoparticles undergo charge equilibration when they are in contact with metal nanoparticles. Such a charge distribution has direct influence in dictating the energetics of the composite by shifting the Fermi level to more negative potentials. The transfer of electrons to Au nanoparticles has now been probed by exciting TiO(2) nanoparticles under steady-state and laser pulse excitation. Equilibration with the C(60)/C(60)(-) redox couple provides a means to determine the apparent Fermi level of the TiO(2)-Au composite system. The size-dependent shift in the apparent Fermi level of the TiO(2)-Au composite (20 mV for 8-nm diameter and 40 mV for 5-nm and 60 mV for 3-nm gold nanoparticles) shows the ability of Au nanoparticles to influence the energetics by improving the photoinduced charge separation. Isolation of individual charge-transfer steps from UV-excited TiO(2) --> Au --> C(60) has provided mechanistic and kinetic information on the role of metal in semiconductor-assisted photocatalysis and size-dependent catalytic activity of metal-semiconductor nanocomposites.
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paper_title: Photocatalytic deposition of Ag nanoparticles on TiO2: Metal precursor effect on the structural and photoactivity properties

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Abstract A series of 1 wt.% Ag–TiO 2 photocatalysts were obtained by photodeposition using different organic (acetylacetonate, Ag-A) and inorganic (nitrate, Ag-N, and perchlorate, Ag-C) silver precursors in order to determinate the influence of the silver precursor on final properties of the photocatalysts. The resulting photocatalytic materials were characterized by different techniques (UV–Vis DRS, TEM/HRTEM and XPS) and their photocatalytic activity was evaluated in the degradation of rhodamine B (used as model pollutant) in aqueous solution under simulated solar light. The photocatalytic reduction of Ag species to Ag 0 on TiO 2 was higher with silver nitrate as precursor compared to acetylacetonate or perchlorate. All the Ag-modified TiO 2 photocatalysts exhibited a surface plasmon resonance effect in the visible region (400–530 nm) indicating different metal particle sizes depending on the Ag precursor used in their synthesis. A higher photocatalytic activity was obtained with all the Ag/TiO 2 samples compared with non-modified TiO 2 . The descending order of photocatalytic activity was as follows: Ag-A/TiO 2 ≈ Ag-N/TiO 2 > Ag-C/TiO 2 > TiO 2 -P25. The enhanced photoactivity was attributed to the presence of different amounts Ag 0 nanoparticles homogeneously distributed on Ag 2 O and TiO 2 , trapping the photogenerated electrons and avoiding charge recombination.
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paper_title: Effect of silver-doping on the crystal structure, morphology and photocatalytic activity of TiO2nanofibers

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In this study, effect of sliver-doping on the crystal structure, the nanofibrous morphology and the photocatalytic activity of titanium oxide nanofibers have been investigated. Silver-doped TiO2 nanofibers having different silver contents were prepared by calcination of electrospun nanofiber mats consisting of silver nitrate, titanium isopropoxide and poly(vinyl acetate) at 600 °C. The results affirmed formation of silver-doped TiO2 nanofibers composed of anatase and rutile when the silver nitrate content in the original electrospun solution was more than 3 wt%. The rutile phase content was directly proportional with the AgNO3 concentration in the electrospun solution. Negative impact of the silver-doping on the nanofibrous morphology was observed as increase the silver content caused to decrease the aspect ratio, i.e. producing nanorods rather nanofibers. However, silver-doping leads to modify the surface roughness. Study of the photocatalytic degradation of methylene blue dye clarified that increase the silver content strongly enhances the dye oxidation process.
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paper_title: Mechanistic Insight into the TiO2 Photocatalytic Reactions: Design of New Photocatalysts

paper_content:

Titanium dioxide (TiO2) has been extensively investigated for the photocatalytic purification of air and water. In this article, we have focused on the mechanisms of the one-electron redox reactions of organic compounds during the TiO2 photocatalytic reactions and on the development of TiO2-based materials. It was clearly demonstrated that the adsorption dynamics of substrates and intermediates, the electronic interaction between TiO2 and adsorbates, and the band structure and morphology of TiO2 nanomaterials are crucial factors for establishing efficient photocatalytic reaction systems. The TiO2-based hybrid nanoparticles with various functional materials, such as polyoxometalates (POMs) and cyclodextrins (CDs), have been fabricated on the basis of the mechanistic aspects. New experimental methods, such as two-color two-laser flash photolysis and single-molecule fluorescence techniques, for the investigation of the TiO2 photocatalytic reactions have been demonstrated.
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paper_title: Oriented 2.0.0 Cu2O nanoplatelets supported on few-layers graphene as efficient visible light photocatalyst for overall water splitting

paper_content:

Abstract Cu2O nanoplatelets with preferential 2.0.0 facet orientation supported on few layers graphene were prepared as films in a single step by pyrolysis at 900 °C under inert atmosphere of Cu2+-chitosan precursor. C u 2 O ¯ /fl-G films exhibit a photocatalytic activity for overall water splitting of 19.5 mmol/gCu+G h. This value is about 4 orders of magnitude higher than the photocatalytic activity measured for unoriented Cu2O nanoparticles on few-layers graphene or than commercial Cu2O nanoparticles and about three orders of magnitude higher than the activity reported in the literature for Cu2O nanoparticles. In addition Cu2O nanoparticles on few-layers graphene retain about 50% of its photocatalytic activity after 6 days of continuous irradiation. It is proposed that this activity and stability arises from the combination of features derived from the pyrolysis preparation procedure including strong Cu2O–graphene grafting, the role of graphene as cocatalyst and preferential 2.0.0 facet orientation.
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paper_title: Carbon-based quantum dots for fluorescence imaging of cells and tissues

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Carbon dots (or carbon quantum dots in some literature reports), generally small carbon nanoparticles with various surface passivation effects, have attracted widespread attention in recent years, with a rapidly increasing number of research publications. The reported studies covered many aspects of carbon dots, from the development of many new synthetic methodologies to an improved mechanistic elucidation and to the exploration of application opportunities, especially for those in the fluorescence imaging of cells and tissues. There have also been significant advances in the establishment of a shared mechanistic framework for carbon dots and other carbon-based quantum dots, graphene quantum dots in particular. In this article, representative recent studies for more efficient syntheses of better-performing carbon dots are highlighted along with results from explorations of their various bioimaging applications in vitro and in vivo. Similar fluorescence properties and potential imaging uses of some graphene quantum dots are also discussed, toward a more consistent and uniform understanding of phenomenologically different carbon-based quantum dots.
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paper_title: Graphene/semiconductor nanocomposites (GSNs) for heterogeneous photocatalytic decolorization of wastewaters contaminated with synthetic dyes: A review

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Abstract The advent of graphene revolution in recent years has opened up immense possibilities for creating and exploring new carbon-based materials for innovative technological applications. Recent advancements have shown that graphene/semiconductor nanocomposites (GSNs) can be envisaged as a promising new class of catalysts for the heterogeneous photocatalytic treatment of industrial wastewaters. While GSNs have been found effective in degrading and mineralizing a myriad of organic contaminants, photocatalytic degradation of synthetic colorants has been most extensively investigated. We present here the state-of-art review on GSNs in the context of photodecolorization of textile effluents. Various approaches to the synthesis of GSNs are first integrated and demonstrated by representative examples. The efficacy of these composite photocatalysts in decomposing selected dye pollutants is then discussed. We conclude the review by emphasizing the future research challenges and opportunities toward the large-scale commercialization of GSNs.
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paper_title: Visible-light photoconversion of carbon dioxide into organic acids in an aqueous solution of carbon dots.

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Carbon "quantum" dots (or carbon dots) have emerged as a new class of optical nanomaterials. Beyond the widely reported bright fluorescence emissions in carbon dots, their excellent photoinduced redox properties that resemble those found in conventional semiconductor nanostructures are equally valuable, with photon-electron conversion applications from photovoltaics to CO2 photocatalytic reduction. In this work we used gold-doped carbon dots from controlled synthesis as water-soluble catalysts for a closer examination of the visible-light photoconversion of CO2 into small organic acids, including acetic acid (for which the reduction requires many more electrons than that for formic acid) and, more interestingly, for the significantly enhanced photoconversion with higher CO2 pressures over an aqueous solution of the photocatalysts. The results demonstrate the nanoscale semiconductor-equivalent nature of carbon dots, with excellent potential in energy conversion applications.
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paper_title: Perovskite Oxide Nanosheets with Tunable Band-Edge Potentials and High Photocatalytic Hydrogen-Evolution Activity.

paper_content:

Perovskite nanosheets of HCa2-xSrxNb3O10 and HCa2Nb3-yTayO10 with controlled band-edge potentials are prepared by H+ exchange (1 M HNO3, 1 week) of KCa2-xSrxNb3O10 which itself is prepared by a polymerized complex method involving a MeOH solution of NbCl5 and TaCl5 to which CaCO3, SrCO3, KCl, ethylene glycol, and anhydrous citric acid are added (400 K) followed by calcination of the produced transparent resin in air (Al2O3 crucible, 1.
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paper_title: Hierarchical Porous TiO2 Embedded Unsymmetrical Zinc–Phthalocyanine Sensitizer for Visible-Light-Induced Photocatalytic H2 Production

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In this study, a novel visible-light-driven photocatalyst was designed based on unsymmetrical zinc–phthalocyanine photosensitizer on hierarchical porous TiO2 (HPT) semiconductor. The HPT material has been prepared by a simple self-formation route. The present work successfully uses zinc phthalocyanine with spectral response extended to 700 nm triggers light harvesting center and HPT semiconductors for high photocatalytic H2 production. This novel unsymmetrical zinc–phthalocyanine (PCH001) containing three tert-butyl and two carboxylic acid groups that act as “push” and “pull” electron transfer properties from the excited dye to the TiO2 conduction band. The carboxylic group in the sensitizer serves as an anchoring group on to the surface of TiO2 and to provide intimate electronic coupling between its excited-state wave function and the conduction-band manifold of the semiconductor. The excellent photophysical properties was governed further by choosing three tert-butyl groups which tuned the LUMO level of...
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paper_title: Carbon "quantum" dots for optical bioimaging.

paper_content:

Carbon dots, generally referring to small carbon nanoparticles with various levels of surface passivation, have emerged as a new class of quantum dot-like fluorescent nanomaterials. Since the original report in 2006, carbon dots have been investigated by many research groups worldwide, with major advances already made in their syntheses, structural and mechanistic understandings, and evaluations for biocompatibilities and potential bio-applications. In this article, representative studies responsible for these advances in the development and understanding of carbon dots are reviewed, and those targeting the use of carbon dots as high-performance yet nontoxic fluorescence agents for optical bioimaging in vitro and in vivo are highlighted and discussed.
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paper_title: Rapid Preparation of Perovskite Lead Niobate Nanosheets by Ultrasonic‐Assisted Exfoliation for Enhanced Visible‐Light‐Driven Photocatalytic Hydrogen Production

paper_content:

Ultrathin perovskite lead niobate nanosheets, (TBA/H)Pb2Nb3O10, were rapidly prepared by novel high-power ultrasonic exfoliation of layered HPb2Nb3O10, and were used as a photocatalyst for hydrogen production from methanol solution under visible light irradiation (λ>415 nm) for the first time. When compared with bulk HPb2Nb3O10, the nanosheets showed same tetragonal crystal structure, but dramatic decrease in thickness and two times higher photocatalytic hydrogen evolution activity. Enhanced photocatalytic performance resulted from the fact that the photoexcited electrons were more efficiently separated and utilized for H2 production on the nanosheets, owing to shorter migration distance of photoexcited electrons.
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paper_title: Self-regenerated solar-driven photocatalytic water-splitting by urea derived graphitic carbon nitride with platinum nanoparticles

paper_content:

A natural self-regeneration step for urea derived graphitic carbon nitride with platinum nanoparticles is found by simply opening the system to air in the dark under ambient conditions, following its solar-driven hydrogen production. The produced peroxides deactivate the graphitic carbon nitride. Release of weakly bound peroxides on the polymeric semiconductor surface is a crucial process for regeneration.
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paper_title: Metal-Free Efficient Photocatalyst for Stable Visible Water Splitting via a Two-Electron Pathway.

paper_content:

Nanocomposites of carbon nanodots embedded in a C3N4 matrix are prepared by heating a mixture of ammonia-treated carbon nanodots and urea powder at 550 °C for 3 h in an alumina crucible.
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paper_title: Synthesis and Photocatalytic Activity of Rhodium-Doped Calcium Niobate Nanosheets for Hydrogen Production from a Water/Methanol System Without Cocatalyst Loading.

paper_content:

Rhodium-doped calcium niobate nanosheets are obtained by exfoliation of layered KCa2Nb3-xRhxO10-δ (x = 0—0.15).
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paper_title: Photoluminescence properties of graphene versus other carbon nanomaterials.

paper_content:

Photoluminescent nanomaterials continue to garner research attention because of their many applications. For many years, researchers have focused on quantum dots (QDs) of semiconductor nanocrystals for their excellent performance and predictable fluorescence color variations that depend on the sizes of the nanocrystals. Even with these advantages, QDs can present some major limitations, such as the use of heavy metals in the high-performance semiconductor QDs. Therefore, researchers continue to be interested in developing new QDs or related nanomaterials. Recently, various nanoscale configurations of carbon have emerged as potential new platforms in the development of brightly photoluminescent materials. As a perfect π-conjugated single sheet, graphene lacks electronic bandgaps and is not photoluminescent. Therefore, researchers have created energy bandgaps within graphene as a strategy to impart fluorescence emissions. Researchers have explored many experimental techniques to introduce bandgaps, such as cutting graphene sheets into small pieces or manipulating the π electronic network to form quantum-confined sp(2) "islands" in a graphene sheet, which apparently involve the formation or exploitation of structural defects. In fact, defects in graphene materials not only play a critical role in the creation of bandgaps for emissive electronic transitions, but also contribute directly to the bright photoluminescence emissions observed in these materials. Researchers have found similar defect-derived photoluminescence in carbon nanotubes and small carbon nanoparticles, dubbed carbon "quantum" dots or "carbon dots". However, they have not systematically examined the emissions properties of these different yet related carbon nanomaterials toward understanding their mechanistic origins. In this Account, we examine the spectroscopic features of the observed photoluminescence emissions in graphene materials. We associate the structural characteristics in the underlying graphene materials with those emission properties as a way of classifying them into two primary categories: emissions that originate from created or induced energy bandgaps in a single graphene sheet and emissions that are associated with defects in single- and/or multiple-layer graphene. We highlight the similarities and differences between the observed photoluminescence properties of graphene materials and those found in other carbon nanomaterials including carbon dots and surface defect-passivated carbon nanotubes, and we discuss their mechanistic implications.
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paper_title: State-of-the-Art Progress in Diverse Heterostructured Photocatalysts toward Promoting Photocatalytic Performance

paper_content:

Semiconductor photocatalysts have received much attention in recent years due to their great potentials for the development of renewable energy technologies, as well as for environmental protection and remediation. The effective harvesting of solar energy and suppression of charge carrier recombination are two key aspects in photocatalysis. The formation of heterostructured photocatalysts is a promising strategy to improve photocatalytic activity, which is superior to that of their single component photocatalysts. This Feature Article concisely summarizes and highlights the state-of-the-art progress of semiconductor/semiconductor heterostructured photocatalysts with diverse models, including type-I and type-II heterojunctions, Z-scheme system, p–n heterojunctions, and homojunction band alignments, which were explored for effective improvement of photocatalytic activity through increase of the visible-light absorption, promotion of separation, and transportation of the photoinduced charge carries, and enhancement of the photocatalytic stability.
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paper_title: Oxidative Polyoxometalates Modified Graphitic Carbon Nitride for Visible-Light CO2 Reduction.

paper_content:

Developing a photocatalysis system for converting CO2 to valuable fuels or chemicals is a promising strategy to address global warming and fossil fuel consumption. Exploring photocatalysts with high-performance and low-cost has been two ultimate goals toward photoreduction of CO2. Herein, noble-metal-free polyoxometalates (Co4) with oxidative ability was first introduced into g-C3N4 resulted in inexpensive hybrid materials (Co4@g-C3N4) with staggered band alignment. The staggered composited materials show a higher activity of CO2 reduction than bare g-C3N4. An optimized Co4@g-C3N4 hybrid sample exhibited a high yield (107 μmol g-1 h-1) under visible-light irradiation (λ ≥ 420 nm), meanwhile maintaining high selectivity for CO production (94%). After 10 h of irradiation, the production of CO reached 896 μmol g-1. Mechanistic studies revealed the introduction of Co4 not only facilitate the charge transfer of g-C3N4 but greatly increased the surface catalytic oxidative ability. This work creatively combined g-C3N4 with oxidative polyoxometalates which provide novel insights into the design of low-cost photocatalytic materials for CO2 reduction.
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paper_title: Strontium Titanate Based Artificial Leaf Loaded with Reduction and Oxidation Cocatalysts for Selective CO2 Reduction Using Water as an Electron Donor.

paper_content:

Thin film of SrTiO3 nanorods loaded with reduction and oxidation cocatalysts drove the selective reduction of carbon dioxide (CO2) into carbon monoxide (CO), as well as caused the production of equivalent oxygen molecules through water oxidation under UV irradiation. The described film functioned as a free-standing plate without any bias potential application, similar to a natural leaf. The film was facilely fabricated by a simple hydrothermal and annealing treatment of a titanium substrate to produce the SrTiO3 nanorod film (STO film) followed by two steps of loading the reduction and oxidation cocatalysts onto the surface of the STO. As a reduction cocatalyst, a CuxO nanocluster was chosen to achieve selective reduction of CO2 into CO, whereas a cobalt- and phosphate-based cocatalyst (CoPi) facilitated oxidation on the STO surface to promote oxygen generation. For the photocatalysis test, a wireless film was simply set into an aqueous solution bubbled with CO2 in a reactor, and CO production was observed in the headspace of the reactor under UV irradiation. Compared to the bare STO film, the dual cocatalyst-loaded STO film exhibited 2.5 times higher CO generation. H2 production was very limited in our system, and the amount of molecules generated by the reduction reaction was almost twice that of the generated oxygen molecules, proving that water molecules acted as electron donors. Our artificial leaf consists of abundant and nontoxic natural elements and represents the first achievement of stoichiometric CO2 reduction using water as an electron donor by a free-standing natural leaflike plate form.
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paper_title: Ring-Shaped Re(I) Multinuclear Complexes with Unique Photofunctional Properties

paper_content:

We synthesized for the first time a series of emissive ring-shaped Re(I) complexes (Re-rings) with various numbers of Re(I) units and various lengths of bridge ligands. The photophysical properties of the Re-rings could be varied widely through changes in the size of the central cavity. A smaller central cavity of the Re-rings induced intramolecular π–π interactions between the ligands and consequently caused a stronger emission and a longer lifetime of the excited state. The Re-rings can function as efficient and durable photosensitizers. The combination of a trinuclear Re-ring photosensitizer with fac-[Re(bpy)(CO)3(MeCN)]+ (bpy = 2,2′-bipyridine) as a catalyst photocatalyzed CO2 reduction with the highest quantum yield of 82%.
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paper_title: Surface engineered CuO nanowires with ZnO islands for CO2 photoreduction.

paper_content:

Large arrays of massively parallel (108 cm–2) CuO nanowires were surface engineered with dense ZnO islands using a few pulsed cycles of atomic layer deposition (ALD). These nanowires were subjected to UV–vis radiation-based CO2 photoreduction under saturated humidity (CO2 + H2O mixture) conditions. We monitored CO2 to CO conversion, indicating the viability of these nanostructures as potential photocatalysts. High-resolution transmission electron microscopy and atomic force microscopy indicated an island growth mechanism of ZnO epitaxially depositing on pristine, single crystal CuO nanowire surface. Photoluminescence and transient absorption spectroscopy showed a very high density of defects on these ZnO islands which trapped electrons and enhanced their lifetimes. Peak CO conversion (1.98 mmol/g-cat/hr) and quantum efficiency (0.0035%) were observed in our setup when the ZnO islands impinged each other at 1.4 nm (8 cycles of ALD) diameter; at which point ZnO island perimeter lengths maximized as well. A ...
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paper_title: “Green” colloidal ZnS quantum dots/chitosan nano-photocatalysts for advanced oxidation processes: Study of the photodegradation of organic dye pollutants

paper_content:

Abstract Quantum dots (QDs) are semiconductor nanoparticles that are emerging as a new class of fluorescent nanomaterials for environmental applications. Heterogeneous photocatalysis using QDs is an attractive technology for the advanced treatment of water contaminated with organic dyes. In this work, novel nano-photocatalysts based on ZnS QDs functionalized with chitosan were developed using a “green” colloidal chemical method in aqueous media at room temperature. These ZnS/chitosan nano-photocatalysts (ZnS–CHI) were extensively characterized, and the results demonstrated that chitosan was an effective capping ligand for the direct production of water-soluble ZnS QDs with an average nanocrystal size of 3.8 nm. Methylene blue and methyl orange dyes, which were used as model organic pollutants, were effectively oxidized by the photocatalytic activity of the ZnS/chitosan nanostructured systems under UV irradiation. In addition, the ZnS–CHI nano-conjugates exhibited blue photoluminescent behavior upon ultraviolet excitation. Therefore, a “green” facile chemical synthesis of fluorescent nano-photocatalytic materials was developed using an abundant biocompatible polysaccharide that exhibit potential for the photodegradation of hazardous organic pollutants present in wastewater and several other environmentally friendly applications.
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paper_title: Continuous-mode photocatalytic degradation of chlorinated phenols and pesticides in water using a bench-scale TiO2 rotating disk reactor

paper_content:

Abstract Photocatalytic degradation of phenol, chlorinated phenols, and lindane was evaluated in a continuous flow TiO2 rotating disk photocatalytic reactor (RDPR). The RDPR operated at a hydraulic residence time of 0.25 day and at a disk angular velocity of 12 rpm. At low molar feed concentrations (0.038 mmol/l), the removal efficiencies for phenol and chlorinated phenols were in the order of 86% or higher, whereas the removal efficiency for lindane at a feed concentration of 0.016 mmol/l was in the order of 63%. For 2,4,6-trichlorophenol (TCP), an increase in the molar influent concentration resulted in a decrease in removal efficiency but in an increase in removal rate. The degradation rate of 2,4,6-TCP followed a saturation type dependancy with the effluent concentration, suggesting a Langmuir–Hinshelwood (L–H) reaction rate equation. A L–H equation was employed to determine the reaction rate constant and the adsorption coefficient for 2,4,6-TCP. The photonic efficiency increased from 0.68% at an influent concentration of 0.13 mmol/l to 2.06% at an influent concentration of 1.0 mmol/l.
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paper_title: Synthesis of CuO-ZnO nanophotocatalyst for visible light assisted degradation of a textile dye in aqueous solution

paper_content:

An attempt was made to prepare CuO/ZnO nanophotocatalyst for visible light assisted degradation of a textile dye (Acid Red 88) in aqueous solutions by wet impregnation method. The CuO/ZnO samples annealed at 550 °C for 5 h were changed from purple to grey, indicating that CuO clusters on ZnO may not be metallic Cu but it may be CuO-ZnO. Characterization using Transmission Electron Microscopy (TEM), Diffuse Reflectance Spectroscopy (DRS), X-Ray Photo Electron Spectroscopy (XPS) and X-Ray Diffraction (XRD) analysis confirms that only CuO phase is present in the as prepared sample. The prepared CuO-ZnO shows approximately 2 times more photocatalytic activity compared to that of bare ZnO and as well as enhanced photocatalytic activity in the presence of external electron acceptors such as PMS (peroxomonosulphate), PDS (peroxodisulfate), and H2O2 (hydrogen peroxide). Total organic carbon (TOC) experiments also support such enhanced activity.
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paper_title: Fabrication of nanostructured flowerlike p-BiOI/p-NiO heterostructure and its efficient photocatalytic performance in water treatment under visible-light irradiation

paper_content:

Abstract Bismuth-related nanomaterials have received intense attention as potential promising photocatalysts for environment remediation. BiOI is well-known due to efficient photocatalytic activity, high stability, low cost and nontoxicity. In this study, novel nanostructured high-yield visible-light-induced photocatalyst p-BiOI/p-NiO was synthesized by a facile solvothermal method. Several characterization methods, such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX), Fourier Transform Infrared Spectroscopy (FTIR), the Brunauer–Emmett–Teller (BET) surface area, photoluminescence (PL) spectroscopy and UV–vis diffuse reflectance spectroscopy (DRS) were employed to study the phase structures, morphologies and optical properties of the samples. The photocatalytic properties of the as-prepared products were measured with the degradation of acid orange 7 (AO7) at room temperature under visible light illumination. It was found that the NiO amount in the BiOI/NiO composites played an important role in the corresponding photocatalytic properties. The best performance was achieved at 10% content. Enhanced photocatalytic activity of the composites was due to the improved photogenerated carrier separation capacity due to suitable heterojunction formation. In addition the mechanism was proposed for the coupled semiconductors. The reusability of nanophotocatalyst and effects of pH, dye concentration and photocatalyst dosage were also investigated.
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paper_title: Recent progress in design, synthesis, and applications of one-dimensional TiO2 nanostructured surface heterostructures: a review.

paper_content:

One-dimensional TiO2 nanostructured surface heterostructures (1D TiO2NSHs) have been comprehensively studied during the past two decades because of the possible practical applications in various fields, including photocatalysis, dye-sensitized solar cells, sensors, lithium batteries, biomedicine, catalysis, and supercapacitors. Combining extensive advancements in materials science and nanotechnology, a 1D TiO2NSH material with well-controlled size, morphology, and composition has been designed and synthesized. More importantly, its superior properties, including a high aspect ratio structure, chemical stability, large specific surface area, excellent electronic or ionic charge transfer, and a specific interface effect, have attracted a great deal of interest in improving current performance and exploring new applications. In this tutorial review, we introduce the characteristics of 1D TiO2 nanostructures, the design principles for the fabrication of 1D TiO2NSHs, and we also summarize the recent progress in developing synthesis methods and applications of 1D TiO2NSHs in different fields. The relationship between the secondary phase and the 1D TiO2 nanostructure and between the performance in applications and the excellent physical properties of 1D TiO2NSHs are also discussed.
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paper_title: In-situ synthesis of visible-light responsive Ag2O/graphene oxide nanocomposites and effect of graphene oxide content on its photocatalytic activity

paper_content:

Ag2O/graphene oxide nanocomposites, as efficient photocatalysts, were prepared by an in situ method using AgNO3 and graphene oxide as reactants under controlled atmosphere. Graphene oxide is synthesised via an eco-friendly method, and the Ag2O nanoparticles displaying elongated spherical morphology are randomly distributed on the surface of GO. The as-synthesised nanocomposites were characterised by different characterisation techniques. The results proved that the concentration of graphene oxide in starting solution displayed an important role in photocatalytic performance of Ag2O/graphene oxide nanocomposites. The nanocomposite materials were found to exhibit very improved photocatalytic activity for degrading methylene blue (MB) and Rhodamine B (Rh-B) under visible light irradiation. The photocatalytic activities of the composite were higher than that of P25 (a commercial TiO2 as a benchmark photocatalyst). The significantly improved photocatalytic activity of the nanocomposites could be attributed to the high charge separation and suppressed recombination of photogenerated electron-hole pairs due to GO. The effects of reaction parameters such as pH and the effect of different scavengers on the photocatalytic activity of the composite were studied.
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paper_title: Design, fabrication, and modification of nanostructured semiconductor materials for environmental and energy applications.

paper_content:

Considerable effort has been made to design, fabricate, and manipulate nanostructured materials by innovative approaches. The precise control of nanoscale structures will pave the way not only for elucidating unique size/shape-dependent physicochemical properties but also for realizing new applications in science and technology. Nanotechnology offers unprecedented opportunities for improving our daily lives and the environment in which we live. This review mainly describes our recent progress in the design, fabrication, and modification of nanostructured semiconductor materials for environmental applications. Their potential applications in the field of energy are briefly introduced. The scope of this article covers a variety of semiconductor materials, focusing particularly on TiO(2)-based nanostructures (e.g., pure, doped, coupled, nanoporous, mesoporous, hierarchically porous, and ordered mesoporous TiO(2)). The preparation of nanoparticles, hierarchical nanoarchitectures, thin films, and single crystals by sol-gel, microemulsion, hydrothermal, sonochemical, microwave, photochemical, and nanocasting methods is discussed.
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paper_title: A feasibility study on photocatalytic degradation of methyl benzene using N doped TiO2 nanoparticles

paper_content:

Volatile organic compounds (VOCs) are common hazardous pollutants found in air, water and soil. In the present study, laboratory designed batch and continuous photocatalytic degradation of methyl benzene, a major contaminant in water, is demonstrated using N doped TiO2 photocatalyst. The N doped TiO2 photocatalyst was prepared under the sol-gel techniques and characterised by different analytic techniques. Treatment efficiency of N doped TiO2 photocatalyst was carried out under the visible-radiation source using laboratory scale reactors such as batch reactor, fluidised moving bed reactor and packed column bed reactor. The effects of parameters viz., photocatalyst concentration, recovery and reusability of the photocatalyst on degradation of VOCs were studied. Simulated methyl benzene in water showed maximum degradation efficiency of 74% in fluidised moving bed reactor; in the packed bed continuous reactor and batch reactor the values were 40% and 50%, respectively.
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paper_title: Multifunctional biophotonic nanostructures inspired by the longtail glasswing butterfly for medical devices

paper_content:

Numerous living organisms possess biophotonic nanostructures that provide colouration and other diverse functions for survival. While such structures have been actively studied and replicated in the laboratory, it remains unclear whether they can be used for biomedical applications. Here, we show a transparent photonic nanostructure inspired by the longtail glasswing butterfly (Chorinea faunus) and demonstrate its use in intraocular pressure (IOP) sensors in vivo. We exploit the phase separation between two immiscible polymers (poly(methyl methacrylate) and polystyrene) to form nanostructured features on top of a Si3N4 substrate. The membrane thus formed shows good angle-independent white-light transmission, strong hydrophilicity and anti-biofouling properties, which prevent adhesion of proteins, bacteria and eukaryotic cells. We then developed a microscale implantable IOP sensor using our photonic membrane as an optomechanical sensing element. Finally, we performed in vivo testing on New Zealand white rabbits, which showed that our device reduces the mean IOP measurement variation compared with conventional rebound tonometry without signs of inflammation.
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paper_title: Genetic Basis of Melanin Pigmentation in Butterfly Wings

paper_content:

Despite the variety, prominence, and adaptive significance of butterfly wing patterns surprisingly little known about the genetic basis of wing color diversity. Even though there is intense interest in wing pattern evolution and development, the technical challenge of genetically manipulating butterflies has slowed efforts to functionally characterize color pattern development genes. To identify candidate wing pigmentation genes we used RNA-seq to characterize transcription across multiple stages of butterfly wing development, and between different color pattern elements, in the painted lady butterfly Vanessa cardui. This allowed us to pinpoint genes specifically associated with red and black pigment patterns. To test the functions of a subset of genes associated with presumptive melanin pigmentation we used CRISPR/Cas9 genome editing in four different butterfly genera. pale, Ddc, and yellow knockouts displayed reduction of melanin pigmentation, consistent with previous findings in other insects. Interestingly, however, yellow-d, ebony, and black knockouts revealed that these genes have localized effects on tuning the color of red, brown, and ochre pattern elements. These results point to previously undescribed mechanisms for modulating the color of specific wing pattern elements in butterflies, and provide an expanded portrait of the insect melanin pathway.
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paper_title: Continuous-mode photocatalytic degradation of chlorinated phenols and pesticides in water using a bench-scale TiO2 rotating disk reactor

paper_content:

Abstract Photocatalytic degradation of phenol, chlorinated phenols, and lindane was evaluated in a continuous flow TiO2 rotating disk photocatalytic reactor (RDPR). The RDPR operated at a hydraulic residence time of 0.25 day and at a disk angular velocity of 12 rpm. At low molar feed concentrations (0.038 mmol/l), the removal efficiencies for phenol and chlorinated phenols were in the order of 86% or higher, whereas the removal efficiency for lindane at a feed concentration of 0.016 mmol/l was in the order of 63%. For 2,4,6-trichlorophenol (TCP), an increase in the molar influent concentration resulted in a decrease in removal efficiency but in an increase in removal rate. The degradation rate of 2,4,6-TCP followed a saturation type dependancy with the effluent concentration, suggesting a Langmuir–Hinshelwood (L–H) reaction rate equation. A L–H equation was employed to determine the reaction rate constant and the adsorption coefficient for 2,4,6-TCP. The photonic efficiency increased from 0.68% at an influent concentration of 0.13 mmol/l to 2.06% at an influent concentration of 1.0 mmol/l.
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paper_title: Mechanistic insights into plasmonic photocatalysts in utilizing visible light

paper_content:

The utilisation of sunlight as an abundant and renewable resource has motivated the development of sustainable photocatalysts that can collectively harvest visible light. However, the bottleneck in utilising the low energy photons has led to the discovery of plasmonic photocatalysts. The presence of noble metal on the plasmonic photocatalyst enables the harvesting of visible light through the unique characteristic features of the noble metal nanomaterials. Moreover, the formation of interfaces between noble metal particles and semiconductor materials further results in the formation of a Schottky junction. Thereby, the plasmonic characteristics have opened up a new direction in promoting an alternative path that can be of value to the society through sustainable development derived through energy available for all for diverse applications. We have comprehensively prepared this review to specifically focus on fundamental insights into plasmonic photocatalysts, various synthesis routes, together with their strengths and weaknesses, and the interaction of the plasmonic photocatalyst with pollutants as well as the role of active radical generation and identification. The review ends with a pinnacle insight into future perspectives regarding realistic applications of plasmonic photocatalysts.
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paper_title: Synthesis of CuO-ZnO nanophotocatalyst for visible light assisted degradation of a textile dye in aqueous solution

paper_content:

An attempt was made to prepare CuO/ZnO nanophotocatalyst for visible light assisted degradation of a textile dye (Acid Red 88) in aqueous solutions by wet impregnation method. The CuO/ZnO samples annealed at 550 °C for 5 h were changed from purple to grey, indicating that CuO clusters on ZnO may not be metallic Cu but it may be CuO-ZnO. Characterization using Transmission Electron Microscopy (TEM), Diffuse Reflectance Spectroscopy (DRS), X-Ray Photo Electron Spectroscopy (XPS) and X-Ray Diffraction (XRD) analysis confirms that only CuO phase is present in the as prepared sample. The prepared CuO-ZnO shows approximately 2 times more photocatalytic activity compared to that of bare ZnO and as well as enhanced photocatalytic activity in the presence of external electron acceptors such as PMS (peroxomonosulphate), PDS (peroxodisulfate), and H2O2 (hydrogen peroxide). Total organic carbon (TOC) experiments also support such enhanced activity.
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paper_title: Bio-inspired NADH regeneration by carbon nitride photocatalysis using diatom templates

paper_content:

In this report, the bio-inspired photocatalytic regeneration of NADH employing graphitic carbon nitride photocatalysis with a diatom frustule structure was presented. The functional structure was constructed from green and sustainable diatomite (diatom earth) by an “incipient wetness impregnation” method. By using [Cp*Rh(bpy)H2O]2+ as an electron mediator, the NADH yield can reach nearly 100%, with the enzymatically active 1,4-NADH being the only product. Furthermore, even without an electron mediator, a direct electron transfer between graphitic carbon nitride and β-NAD+ was possible and NADH could still be regenerated. Diatom-based carbon nitride showed a substantial improvement in regeneration efficiency compared with mpg-C3N4 which has a higher specific surface area. This was ascribed to the diatom structure, with its enhanced light trapping and scattering promoting high photocatalytic efficiency. Furthermore, abundant species of diatoms in the earth offer more possibilities to construct an artificial photosynthetic system using diatom frustules with excellent light-to-energy conversion efficiency.
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paper_title: Light harvesting in phototrophic bacteria: structure and function.

paper_content:

This review serves as an introduction to the variety of light-harvesting (LH) structures present in phototrophic prokaryotes. It provides an overview of the LH complexes of purple bacteria, green sulfur bacteria (GSB), acidobacteria, filamentous anoxygenic phototrophs (FAP), and cyanobacteria. Bacteria have adapted their LH systems for efficient operation under a multitude of different habitats and light qualities, performing both oxygenic (oxygen-evolving) and anoxygenic (non-oxygen-evolving) photosynthesis. For each LH system, emphasis is placed on the overall architecture of the pigment-protein complex, as well as any relevant information on energy transfer rates and pathways. This review addresses also some of the more recent findings in the field, such as the structure of the CsmA chlorosome baseplate and the whole-cell kinetics of energy transfer in GSB, while also pointing out some areas in need of further investigation.
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paper_title: Recent progress in design, synthesis, and applications of one-dimensional TiO2 nanostructured surface heterostructures: a review.

paper_content:

One-dimensional TiO2 nanostructured surface heterostructures (1D TiO2NSHs) have been comprehensively studied during the past two decades because of the possible practical applications in various fields, including photocatalysis, dye-sensitized solar cells, sensors, lithium batteries, biomedicine, catalysis, and supercapacitors. Combining extensive advancements in materials science and nanotechnology, a 1D TiO2NSH material with well-controlled size, morphology, and composition has been designed and synthesized. More importantly, its superior properties, including a high aspect ratio structure, chemical stability, large specific surface area, excellent electronic or ionic charge transfer, and a specific interface effect, have attracted a great deal of interest in improving current performance and exploring new applications. In this tutorial review, we introduce the characteristics of 1D TiO2 nanostructures, the design principles for the fabrication of 1D TiO2NSHs, and we also summarize the recent progress in developing synthesis methods and applications of 1D TiO2NSHs in different fields. The relationship between the secondary phase and the 1D TiO2 nanostructure and between the performance in applications and the excellent physical properties of 1D TiO2NSHs are also discussed.
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paper_title: Enhanced Light Harvesting in Perovskite Solar Cells by a Bioinspired Nanostructured Back Electrode

paper_content:

Light management holds great promise of realizing high-performance perovskite solar cells by improving the sunlight absorption with lower recombination current and thus higher power conversion efficiency (PCE). Here, a convenient and scalable light trapping scheme is demonstrated by incorporating bioinspired moth-eye nanostructures into the metal back electrode via soft imprinting technique to enhance the light harvesting in organic–inorganic lead halide perovskite solar cells. Compared to the flat reference cell with a methylammonium lead halide perovskite (CH3NH3PbI3−xClx) absorber, 14.3% of short-circuit current improvement is achieved for the patterned devices with moth-eye nanostructures, yielding an increased PCE up to 16.31% without sacrificing the open-circuit voltage and fill factor. The experimental and theoretical characterizations verify that the cell performance enhancement is mainly ascribed by the broadband polarization-insensitive light scattering and surface plasmonic effects due to the patterned metal back electrode. It is noteworthy that this light trapping strategy is fully compatible with solution-processed perovskite solar cells and opens up many opportunities toward the future photovoltaic applications.
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paper_title: Mimicking the Key Functions of Photosystem II in Artificial Photosynthesis for Photoelectrocatalytic Water Splitting.

paper_content:

It has been anticipated that learning from nature photosynthesis is a rational and effective way to develop artificial photosynthesis system, but it is still a great challenge. Here, we assembled a photoelectrocatalytic system by mimicking the functions of photosystem II (PSII) with BiVO4 semiconductor as a light harvester protected by a layered double hydroxide (NiFeLDH) as a hole storage layer, a partially oxidized graphene (pGO) as biomimetic tyrosine for charge transfer, and molecular Co cubane as oxygen evolution complex. The integrated system exhibited an unprecedentedly low onset potential (0.17 V) and a high photocurrent (4.45 mA cm-2), with a 2.0% solar to hydrogen efficiency. Spectroscopic studies revealed that this photoelectrocatalytic system exhibited superiority in charge separation and transfer by benefiting from mimicking the key functions of PSII. The success of the biomimetic strategy opened up new ways for the rational design and assembly of artificial photosynthesis systems for efficient solar-to-fuel conversion.
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paper_title: Single-step optical realization of bio-inspired dual-periodic motheye and gradient-index-array photonic structures.

paper_content:

This Letter demonstrates a single-step optical realization method for hexagonal and square lattice-based dual periodic motheye and gradient-index-array photonic structures over large areas. Computed phase mask of gradient interference patterns are used as inputs to a phase-only spatial light modulator (SLM), and the first-order diffracting beams are coherently superposed with the help of a 2f-2f Fourier filtering setup to avoid complex optical geometry for generation and control of individual beams. The simulated interference patterns are verified experimentally through a CMOS camera. The fabricated micro-structures on a positive photoresist are shown to have a major periodicity of 638 μm and minor periodicity of 25.2 μm, with the air hole diameter varying from 22.7 to 6.9 μm along the X and Y axes. The depth of the fabricated structure gradually varies from 4.203 μm at the center to 1.818 μm at the corner. These structures may be scaled down to submicron features that can show improved anti-reflection properties for solar energy harvesting and GRIN lens for optical wavelength region.
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paper_title: Porphyrin/SiO2/Cp*Rh(bpy)Cl Hybrid Nanoparticles Mimicking Chloroplast with Enhanced Electronic Energy Transfer for Biocatalyzed Artificial Photosynthesis

paper_content:

A biocatalyzed artificial photosynthesis system (APS) based on porphyrin/SiO2/Cp*Rh(bpy)Cl hybrid nanoparticles (TCPP/SiO2/Rh HNPs) to mimic chloroplasts in green plant is reported. The TCPP/SiO2/Rh HNPs are fabricated via sol-gel reaction of silica precursors functionalized with photosensitizer (porphyrin, TCPP) and electron mediator (Cp*Rh(bpy)Cl, M); while the integration of enzyme and coenzyme nicotinamide adenine dinucleotide (NAD)(H), on the outer surface of the HNPs is achieved through electro-static-interaction-driven assembling under the entanglement of a negatively charged polyelectrolyte. The chloroplast-mimicking, highly integrated APS exhibits remarkably superior performance over a free system such that the regeneration of NADH is improved from 11% to 75%, and the synthesis of formic acid from CO2 increased from 15 to 100 mu mol. Based on the detailed investigations into the photochemical and electrochemical properties, it is speculated that the covalent linking of the photosensitizer and electron mediator via silicon hydride bonds, and the formed SiO2 network through sol-gel reaction, may form intramolecular and intermolecular electron transfer chains to direct more efficient electron transfer from TCPP to M. Such intramolecular and intermolecular electrons and energy transfer, cooperated with the integrated biocatalytic process, lead to the significantly enhanced overall reaction efficiency. Moreover, the integrated APS also allows facile recycling of expensive M, enzymes, and cofactors.
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paper_title: Biomimetic polymeric semiconductor based hybrid nanosystems for artificial photosynthesis towards solar fuels generation via CO2 reduction

paper_content:

Abstract In photosynthesis, an intricate polymeric system is constructed by connecting a light-harvesting antenna network, a molecular water oxidation center, and CO 2 or proton-reduction machinery in a nanolayered architecture as a basic photosynthetic unit for solar-to-fuels conversion. Herein, we present a prototype basic artificial photosynthetic unit by connecting a typical CO 2 /proton reduction catalyst, a cocatalyst and an electron mediator as well as CO 2 activator into a polymer based nano-architectured system for artificial photosynthesis with water and CO 2 . Here, g-C 3 N 4 nanosheets, mimicking the nanolayered thylakoids stacks are demonstrated as promising photocatalytic elements with planar configuration and high surface area, which provide an excellent platform for the assembly of other analogous elements. Au NPs are served as a suitable cocatalyst. ZIF-9, as a typical cofactor to illustrate this concept here, is used as a CO 2 concentrator and an electron mediator to promote the redox reaction. In artificial photosynthesis, driven by light energy, water and CO 2 are served electron donor and carbon source respectively for the generation of H 2 and CO. The artificial unit described here as a simple model, provides an important biomimetic step down a path aligned with the low-cost artificial photosynthetic systems manufacturing.
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paper_title: Bioinspired Photoelectric Conversion System Based on Carbon-Quantum-Dot-Doped Dye–Semiconductor Complex

paper_content:

Compared to nature’s photoelectric conversion processes, artificial devices are still far inferior in efficiency and stability. Inspired by light absorption and resonance energy transfer processes of chlorophyll, we developed a highly efficient photoelectric conversion system by introducing Carbon quantum dots (CQDs) as an electron transfer intermediary. Compared with conventional dye-sensitized semiconductor systems, the present CQD-doped system showed significantly higher photoelectric conversion efficiency, as much as 7 times that without CQDs. The CQD-doped dye/semiconductor system may provide a powerful approach to the development of highly efficient photoelectric devices.
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paper_title: Design, fabrication, and modification of nanostructured semiconductor materials for environmental and energy applications.

paper_content:

Considerable effort has been made to design, fabricate, and manipulate nanostructured materials by innovative approaches. The precise control of nanoscale structures will pave the way not only for elucidating unique size/shape-dependent physicochemical properties but also for realizing new applications in science and technology. Nanotechnology offers unprecedented opportunities for improving our daily lives and the environment in which we live. This review mainly describes our recent progress in the design, fabrication, and modification of nanostructured semiconductor materials for environmental applications. Their potential applications in the field of energy are briefly introduced. The scope of this article covers a variety of semiconductor materials, focusing particularly on TiO(2)-based nanostructures (e.g., pure, doped, coupled, nanoporous, mesoporous, hierarchically porous, and ordered mesoporous TiO(2)). The preparation of nanoparticles, hierarchical nanoarchitectures, thin films, and single crystals by sol-gel, microemulsion, hydrothermal, sonochemical, microwave, photochemical, and nanocasting methods is discussed.
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Title: A review on the progress of nanostructure materials for energy harnessing and environmental remediation

Section 1: Introduction
Description 1: Overview of the global energy and water demand issues, and introduction to photocatalysis and nanomaterials for energy and environmental applications.

Section 2: Classical photocatalysts
Description 2: Discussion about traditional inorganic photocatalysts, including metal oxides, sulphides, phosphides, selenides, oxynitrides, nitrides, phosphates, and halides.

Section 3: Carbon-based nanomaterials
Description 3: Examination of carbon-based nanomaterials such as fullerenes, carbon nanotubes (CNTs), graphene, and their role in enhancing photocatalytic activity.

Section 4: Modifications in photocatalysts
Description 4: Explanation of various modification techniques in photocatalysts to increase quantum efficiency, including metal and non-metal doping, co-catalyst loading, and heterojunction structures.

Section 5: Synthesis of nanostructure materials
Description 5: Overview of synthesis techniques for nanostructured materials, such as chemical vapor deposition, sol-gel, pyrolysis, hydrothermal, solvothermal, microwave-assisted synthesis, sonochemical, microemulsion, arc discharge, electrodeposition, polyol synthesis, exfoliation, and ball milling.

Section 6: Mechanistic features
Description 6: Discussion on the relationship between mechanistic features of nanomaterials and their synthesis methods, with a focus on quantum dots, thin films, one-dimensional, and multidimensional hierarchical hybrid materials.

Section 7: Application of nanostructured materials
Description 7: Detailed overview of applications of nanostructured materials in energy conservation and generation, specifically for water splitting, artificial photosynthesis, and photoreduction of CO2.

Section 8: Nanostructure photocatalysts for water and wastewater treatment
Description 8: Explanation on the use of nanostructured photocatalysts for water and wastewater treatment, including the degradation of recalcitrant organics and addressing common challenges.

Section 9: Future prospect
Description 9: Insight into future prospects of nanotechnology in solving environmental and energy crises, emphasizing biomimicking and innovative designs for enhanced photon energy harvesting.

Section 10: Conclusion
Description 10: Summary of the review discussing the unique properties of nanostructured materials, their potential benefits, economic feasibility, and future directions in nanotechnology.