Layer-by-Layer Electroactive Thin Films to Layered Carbon Electrodes


Tarek R. Farhat Department of Chemistry, University of Memphis

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The science of depositing thin polymer films over the surface of electrodes is widely used by electrochemists for sensor technology. Applications include studying mass transport of molecules across these films, thin-film electrochemical detection, and electroactive sites or species embedded within the polymer backbone. Electroactivity of thin polymer films on the surface of inert electrodes is the major topic covered in this article with emphasis on polyelectrolytes, ion complexes, and colloids. Thin films discussed here are not of the classical ion-exchange type, nor their composites or complexes. It focuses on layer-by-layer (LBL) thin films introduced by Decher, Hong, and Schmitt, where many different types of polyelectrolytes, ion complexes, and colloids are alternately deposited to assemble multilayer thin films. Even at this juncture research has diversified and segregating electroactive LBL thin films into separate families or categories would be helpful to scientists browsing this field. Because of the intensive work done on electroactive LBLs, the article discusses briefly each citation with emphasis on the newly fabricated “carbon–polymer electrodes.” It includes as many references as possible starting from the early 1990s when the LBL field was born. In all the topics discussed, emphasis is made on the chemicals involved in making the LBL thin film, the type of the electrode used and the functionalization needed for thin film deposition, the application of cyclic voltammetry, and the type of electroactive or electrocatalytic center involved.

Topics that are covered in this article comprise LBL thin films containing:

  1. Phthalocyanin, porphyrins, and dendrimers

  2. Electroactive complex salts

  3. Polyoxometallates

  4. Redox polymers

  5. Metallic, semiconductor, and metal-oxide colloids

  6. Conducting polymers

  7. Graphite oxide and graphite carbon colloids

In each case a brief introduction is given about the mechanism of assembly and the electrochemical activity of the chemical species involved.