Today we're opening a Target Mystery Booster Box. What's up guys, we're back with another epic video. Today we're opening a Target Mystery Booster Box, which is, what is that? I mean, what is a Mystery Booster Box? So what I did, I grabbed a bunch of mystery blisters from Target. We're gonna open up enough to equal a booster box. So 24 packs. We're gonna compare it to regular booster box ratios, see what we can pull and if it's gonna be any better. But first we have a giveaway. I'll be giving away these three cards.  Let me know what you think about the Mystery Booster Box if it's better or if it's worse than a regular booster box. Let's hop right into it. So a couple of these, I think three of these are legacy. So we're gonna have two of those legacy packs. Then we're gonna have the triple packs but sometimes have like mega packs in them and stuff. So this should be pretty interesting. It's gonna be a lot different than a regular booster box. Let's start off with one of these because we have six of these. So six of these three pack ones. There's also bonus cards. So you don't get that in a regular booster box. So I feel like this has a little bit of an edge if we can actually get something good out of there. We have a triple star try-on. Okay, not the most exciting. Then we have a mega tent. Oh, dual power. That's cool. And a soul fusion, which seems to always be in these. Let's start off with the soul fusion. Let's see what we can pull. Can we get, isn't there, yeah. Panker tops as a common. We've got some nice Thunder Dragon stuff. What else is in here? Agave Dragon Gokipold. Oh, the Chaos Dragon, Levionier. First edition Secret Rare. That's a card that's in here. Yep, that's a card. Okay, that's pretty good. First edition, this card looks really good. Some might argue this looks better than the Ulti. Let me know in the comments which one you like more. I really like this version. I also like the Ulti, so it's hard to decide. But that's a really good pull. I don't think I've ever even pulled that. So that's like a first. I've only ever owned the unlimited of that version. So that's pretty cool. All right, we're starting this thing off hot. Here we go. We've got the Star Seraph Sovereignty. I always thought this was a weird card. This is a chair. The King Calamity. Necrozovacris. Galaxy Eyes Full Armor Photon Dragon. And the Signal Warrior. All right, Megaton 2018. Is there anything in 2018? I feel like 2017 was really good. I can't remember about 2018. We have the Accumulator. Call of the Archv. Trading Places. Chosen by the World Chalice. Zambina. Galaxy Worm. Alter Guys Hexia. Pendulum Paradox.  I was about to forget. Arrival Rival School. One-time passcode. We got it. Looks like an Apple symbol almost even though it's a scapegoat. It looks very similar. The Flick Clown. The Legendary. Difficult to notice what his name actually is. Onto the next pack. This is a good start. Good start. Chaos Dragon. Levionier. Oh, struggle is real. Let's see. All right, we have the Mist Valley Executor. Very cool. Now we have another Infinity Chaser. It's cool. We have to be dual. That's terrible. And then Sulfusion. So we will start with Speed Duel. What we don't want to see. We would much rather see like dual power like the last one. That's a lot, a lot better. Slot Machine Impress Mantis Fire Reaper. And a Koishi. Wow, that's actually a good one. I think it's like $3. Could be more honestly because this is a pretty good card in Speed Duel and in general like go format. So let's go into Sulfusion. I think Infinity Chasers has some cool stuff. Sulfusion has been good to us so far. Can we pull something else? There's no like Ultis or Secrets or I mean Starlights or Collectors or anything but there is Secrets obviously. Token Collector. And Necro Valley Throne. There's a Super Rare. Can't remember if that's any good Grave Keepers Spiritualist. Wow, those Grave Keepers. Pretty cool.  We're going to chase Infinity. Can we pull something good? We have Hidden Armory. Marshaling Field. Mythical Beasts Jackal King. Infinity Track Mountain Smasher in. Infinity Attack. Infinity Track. There we go. Infinity Track is a trencher. Cool. Some of these are actually worth something. Contribute one Earth Monster special summon this card from your hand in defense position. We have to tribute to do that. This is a card from Garotar 1. Infinity Track in the graveyard. Okay, interesting. Okay, it doesn't seem generically good but maybe it's good in the archetype, not really sure. Okay, let's try ourselves a Legacy Pack. We have Spell Ruler and Believe Invasion of Chaos in here. So far this booster box we've already pulled one big card. Okay, so we have a Ring of Defense. Very nice. Spell Ruler and Invasion of Chaos. So we pulled, you know, Chaos Dragon, Levionaire. We pulled a couple other decent things. So not incredible, not terrible. We got a Kothodama and Uruka. Metal Fish. Oh wait, we should do the pack trick here. So we don't ruin it. Here we go. We got the Tailor of the Thickle. Formants of Sword. Love it. Hamburger Recipe. Igaboon. Metal Fish. Horn of Light and UFO Turtle. All right, I'm done on that one. That's fine because we're about to pull Chaos Emperor Dragon. We've had good luck with Dragon's Secret Rear. Just saying. We've already pulled one. So let's do it now. We're going to start with this way. Okay, we're going to go into the Griffin's Feather Duster. We're going to go to Grandora. We're going to go to Neobug. Salvage. We're going to salvage this opening. Not that it really needs it. We have Chaos Dragon. Let me near Dr. Chaos. Insect Princess. The legendary Ultra Rear Insect Princess. The one that you really, yeah, you always want this over BLS. You want it over DMock, Chaos Emperor Dragon. Yeah, this is the card you want. Insect Princess. Back to the Triple Blisters. We're doing pretty good so far. I mean, in Ultra Rear, even though it is Insect Princess, still pretty good. Not the worst thing ever. So here's our promo. It is an ant draw. Cool. Then we have what? Please don't be speed duel. It's speed duel. And we have a hidden arsenal six. It's pretty old, but it's hidden arsenal. You guys know a lot of the hidden arsenals are not great. Let's see what we can do. Also, they're always very warped, which is annoying. So we have Gatekeeper. That guy is really cool. I really like this dude. An indestructible mechanoid created for the sole purpose of guarding the gateway. So he's like Gate Guardian, but like mini Ketetsu and release restraint. Very cool. He's like a mini Gate Guardian. He's from like one of the tournament packs. So he's pretty old. We have, oh, there's our secret. We've got the Kotal, Vylon, Vylon and Fusion. Okay. A little bit warped. That's why I don't really like those cards because like, if you use them, you got to really like work on them to be not warped anymore. Okay. We've got the Capotera, Galaxy Bray, Astonado, Edgym, Orcus Symbol, and Noble Knight Evane. Oh, that's pretty cool. It's got a Lion, Noble Knight Evane. I don't know how to say that, but that she or he, what is he or she? I don't know. They have a Lion between them. How about that? Yeah. Let's just move on. I don't know. On to the next one. That was confusing, but all I know is it was cool. It was trying to say it was cool and I just ruined it. Made it not cool at all. There's another N'Churriant jaw it looks like. Let's see. Oh, no. It's Triple Shard Trion again. Dual Power. Okay. We like this one. So if it's this three, you get the Trion every time. Is that how that works? We're about to find out, I guess. Let's start off with the Soul Fusion. Last time we did this, with this specific setup of pack, with that promo, we got the Levineer. Let's see. Jack Jaguar. Gift. Crawler. Until Noble Arms. Grave Keepers. Headman. A lot of Grave Keepers. Thunder Dragon Duo. Another Quilt Thunder Dragon. We got Salamangrae Falco. Man, that was a Salamangrae pack if I've ever seen one. All right. Let's try the Dual Power. Let's see what we can get. There's some good cards in here for sure. There's some really good cards. Goki Jet Ogre. Predapent Orphous Scorpio. We've got the Hieratic Seal of Heavenly Spheres. There's a good one. That might be our good card. Fright for Patchwork and Night. Oh, Naruto's in here. Job Naruto. That's pretty cool. And the 2018 Mega Tin Pack. What will this booster box yield us? I think we're getting way more foils because we're getting like cards that are, or packs that are guaranteed foils and stuff self-destruct. And Goki Headbat. Scrabble Egg. Air Cracking Storm. All those guys' protocol. Oh! Heavy Metaphones Electromite and a Spellbook of Knowledge. That's pretty good. And World Chalice the World Chalice I think is actually okay too. Okay, so we get the Electromite. This card I believe is still banned. This is the reprint. But if it does get unbanned, then maybe this will be worth something. It's still worth a couple bucks, even banned. So Spellbook of Knowledge. That's another one that's been worth stuff for a while. That's pretty good. And then this card was worth a dollar for a while. I don't know if it still is, but you guys will find out during the video. But that is a pretty amazing 2018 pack. We are actually crushing this opening right now. Oh my goodness. This is incredible. We are pulling insane. All right, we're ready. We got to get our Pendulums ready. Let's go! Just in case Trif and you know what to do or something. All right, Mirror Force Dragon. Very cool. Let's go into Spell Ruler. Let's rule the spells by pulling something awesome as a Spell card. One, two, three, which there are many in here. Confiscation, Delinquent Duo, Forceful Sentry, Tune World, all that stuff. Electric Snake is definitely not a spell. Liable Guardian. Guardian of the Throne Room. Upstar, that's good. And that was the last card. Okay, Upstar's pretty good. Now we go to Invasion of Chaos. Can we pull something insane? We have not pulled anything insane from Invasion of Chaos in a while for us.  Self-destruct. Got the Lord Poison. Thunder. Riot Coakie. Gigantus. Yellow Luster. Anti-aircraft craft craft craft. I don't know. This is actually worth like two or three dollars, I think. The Berserk Gorilla. Ooh, I think it actually is. Which is kind of weird, but that's still cool. We still have like what, eight packs left? Couple promos. Yeah. Okay. This looks like a tispey duel. We're about to find out. We got the Oodragonity Javelin. That's better than what we've been getting, I think. Then we have... Battle Pack 3 Monster League. This is terrible. There was a card that I needed in here. I think it was like Spind Gilman for Edison format. I think it's in here. So if we pull it, that'd be insane. Mechlord. Oh, Upside Downbreaker. Very cool. Swords and Electromagnetic Bagworm. There's a lot of cards in this set, like 300 cards. I just noticed Tune Chaos. That's pretty cool. So we'll save that for last. Okay, Soul Fusion. Tune Chaos is pretty big if we can pull something. Let's go with Soul Fusion, which has been pretty good. So far, Galaxy Brave. Galaxy Trance. Summoner Summoner. Sum Sum Summoner. Sum Sum Summoner. Sum Sum Summoner. Okay, let's not start the chant. All right, on to the next one. Tune Chaos. Huge cards in here. Stardust Dragon. Chaos and Bird Dragon. Envoy at the end. And just other amazing collector rares that were printed here. And then like Cypher and GearGam was like $300 out of here. Crossover. Mass Hero Acid. Oh no, it's over so quickly. Okay, Pot of Desires. That sounded weird, but okay. Two more Blister Packs. We've got one more here. Then we have a legacy pack to end it off with. Okay, don't be a speed duel. Don't be a speed duel. We're happy if it's not speed duel. We have speed duel, I think. And then another Javelin. Yeah, we've got a Tune Chaos, but okay. Cool, I'd rather have Battle Pack 3, which is saying something because those are really terrible. This Target Booster Box. How's it doing? Pretty good so far. Dijin. Moray. Imae Ruka. Not Umi Ruka, Imae Ruka. Soul Fusion. Bless us with another amazing secret rare. We usually have pretty good luck out of these Soul Fusion packs. Oh, there's our first Pankratops. We're definitely pulling that out because I think only have one Token Collector. Some Summoner Summoner. Very nice. Again, we've got another Sum Summoner Summoner and we will open the Tune Chaos. Come on, Tune Chaos. I think it's the fourth card. We're going to do this. I think it's that because it appears way too quickly and it's not very interesting. Number 68, Master of Goka. That's a cool card. Prague Leo. Dark Flare Dragon. Cyframe Driver and one final card. Here we go. Fluffle Angel. No. All right, that was a dud, but that's okay. We have two more packs. Let's do this. Two packs, one of them being Spell Ruler, I think. Yeah, and one Invasion Chaos. Then we have Mirror Force Dragon. Let's go with this one. There we go, Spell Ruler. I meant to have some Metal Raiders ones in here. I think I've mixed them up. Oh, well, let's go. One, two, three, four. Let's see how the booster box will do. Come on, Spell Ruler. Have we pulled a foil yet? I don't think so. Fire Crackin. Tailor of the Fickle. Curse of Fiend. Queen Bird. Sonic Bird. Black Illusion Ritual. And there it is. We finally did get a Spell from Spell Ruler. It's the Black Illusion Ritual. You love to see this card. I love this one. It's very nostalgic. And the final pack. Invasion of Chaos from the Target Mystery Booster Box. So far, the mystery has been a pretty good one. Let's see if we can end it off with something insane. I'm down. We have Lord Poison. The Lord of the Poison. The Salmon. The Terror King. Self-Destruct Button. Chaos Necromancer. Burning LGA. Furnace. Furnace. Oh, okay. Oh, Leviah Dragon. Nados. We have pulled this card a lot recently, but it's an ultra rare. We will take that. It seems to be our favorite card from Invasion of Chaos recently. It does look really cool. I think it does. If you guys enjoyed that Epic Target Mystery Booster Box, make sure to subscribe to the channel, because we will have more epicness coming up in the future. Shout out to CCD Trust, Cards of Info Show, Tomato Juice, Noa J, Stanley, Mike, Nance, Mamik, Echo, Duelist, King of Hearts, Banking, McFarland, G-Raider, and Daxter. Thank you guys for supporting the channel, and I'll see you guys next time. Peace.


c catalyst and the photo catalyst. And this second feature, this increase in absorption towards the near IR corresponded to the onset of catalysis. And so you can see, for example here, if these are data measuring, this is the current as a function of applied potential. In the top, you can see the optical signal associated with the first reduction and then the optical signal from the second reduction. This is the pre-catalytic wave. This is the catalytic wave of the redox changes driving water reduction on a ruthenium oxide surface. And in general with the electric catalyst we've studied, we've found and observed both pre-catalytic and catalytic waves and trying to measure the distinction of those two optically is often one of the biggest challenges we have in these measurements. But the nice thing here, of course, is that we're measuring the population of these second reduced species optically. We're measuring the current at the same time and we can plot one against the other. And in this case, we observe that the reaction goes as the second order of the second reduction of these ruthenium oxides. And so if you take the gradient to this plot of the log of absorption change versus the log of current density, the gradient is two for both the electric catalyst and the photoelectric catalyst. And indeed, it's not just a gradient, it's two. If you can overlay these two plots on top of each other, essentially they're both the voltage driven and the light driven reaction. The flux of proton reduction current depends only upon the density of the finium on the surface. Now, the observation that the reaction was second order in the second reduction of the ruthenium oxide allowed us to distinguish rather easily between the two different reaction pathways which people have proposed for these ruthenium oxides. Either a heterolytic or homolytic pathway, we observe a second order behavior which clearly suggests the idea that the two hydrides have to come together to release molecular oxygen. And so this observation of second order behavior very directly gave us an indication of reaction mechanism. If we go on now to return to the topic of water oxidation, then the particular study I'll just introduce to you is a study we've been doing on nickel ion electric catalysts. This is a collaboration with ICIQ in Spain. And the particular thing they observed there was that if they change the doping level of their nickel catalyst with different metal ions as they were to be typically 10% of iron or cobalt, manganese or zinc or indeed the undoped system, then the current density versus voltage varied. And indeed it was well known, iron gives the highest current densities of all these metals. And we wanted to understand why iron gives a higher current density than the other metals, at least in terms of reaction kinetics. Now, the oxidations of the system give rise to optical absorbance changes and we can observe both pre-catalytic and catalytic absorbance changes. But if we just focus on the redox species associated with catalysis, then we can use our optical absorbance measurements and our B.R. Lambert rule to calculate the density of oxidized species as a function of potential. And you can see data here where, so it is, we would assign to the oxidation of nickel OHs to give nickel oxos. And we can see that we need the potential dependence of this oxidation depends upon the metal dopant. Manganese, it turns out, is the easiest to oxidize but to regenerate the highest density of oxidizing species on these nickel foams in the presence of a manganese. Iron, you can oxidize a reasonable density of species on the iron dope system but actually rather less than the manganese. The zinc and the undoped, you need a significantly higher potential to achieve the same sort of densities of nickel oxo species on the surface. If we plot the current density versus the density of oxidized species, in this case, we observe approximately second-order behavior. So it's the idea that as we increase the density of oxidized species on the surface, the rate goes up by a factor of, by the square of the density of those species. And so we have the idea that most likely to rate the terminating step involves two nickel species, two nickel oxo species coming together either nearest neighbor on nickels or maybe because it's a morphostructure on nickels which maybe point towards each other. You could, what's also striking is that in a misanalysis, it becomes obvious why iron is so effective because the current density for the same density of oxidized species is significantly higher for iron than the other materials. It's also notable that these are not perfect second-order behavior. Probably there's some dependencies of a change of enthalpy of the energetic of these nickel species as we change potential but not far off and certainly the iron system shows a pretty much near ideal second-order behavior suggesting that at least the potential range we're looking at here, primarily we're observing a population rather than enthalpy change, driving the change in kinetics with potential. What maybe is most interesting mechanistically is if we plot the turnover frequency we can get from those data versus the energetics and the easiest way to measure the energetics of these systems was to measure the peak of a pre-catalytic wave corresponding to the nickel OH2 getting oxidized to the nickel oxyhydroxide which is a rather direct measure of a nickel-oxygen bond strength. And so what you can see here is one of these classic trumpet plots where you have a maximum for the iron and rather lower turnover frequencies for the manganese cobalt on one side and the undoped and the zinc on the other. And how we can understand the reaction kinetics of this particular trumpet behavior, sorry, volcano behavior is the idea that the manganese and the cobalt dope systems it's rather easy to oxidize these systems to generate the higher oxidized states but those higher oxidized states are not so reactive because they're not oxidizing enough and so they're unable to drive the chemistry of the OO bond formation. Another way of putting this sort of plot is that there's a shift in the OH, in the oxygen binding to the metal center with metal dopant. We think this shift is associated with a change in the local environment of the nickel associated with these nickel ions. You can see that from my analysis that I won't go into that in this talk but this I hope gives you some insight into the idea that you can change these sort of optical measurements allow us to give some insights into how the turn of the frequency can change your potential. And so in this case, we have the idea that the these systems the potential determining step is the key one which limits the reaction the undocked and the nickel are hard to oxidize and so we don't get the reaction is slow because this step is slow whilst the manganese and the cobalt is slow because the states generated these nickel oxide states are not sufficiently reactive to drive the rate determining step. The last topic I thought I just mentioned is a comparison between a electro deposited iridium system and molecular and a molecular dimer of iridium centers on nano ITO. So we're interested in trying to compare the kinetics of essentially molecular sites on an electrode driving water oxidation compared to a conventional heterogeneous film of iridium oxide. Both electrodes oxidize water under an applied potential at similar potentials but current densities are lower because visoridium molecular dimers are there are quite a low density on the surface. But both in both cases, the water oxidation kicks off at a similar potential. Now the spectroscopy of the reading oxide is rather horribly complicated with multiple redox states but if we ignore all that and just focus on the kinetics of the state involved in driving the water oxidation, then we can plot here or we can measure here the decay kinetics of accumulated oxidized species on the iridium oxide both the film or the molecular at open circuits. So we apply a potential you then turn the potential off apply the potential to accumulate both oxidized species we then turn the potential off and we measure the decay of the optical signal as a measure of how quickly those states can oxidize water. And what we observe is that the kinetics on the film depend upon how many iridium oxides we had oxidized at the surface. So what the potential with applied is what the black points here correspond to the decay kinetics of those oxidizing species under the iridium oxide as we go to more positive potentials and accumulate more oxidizing species on the surface then the kinetics accelerate by over on order of magnitude. We can attribute this most obviously to a carbonizer got a typing going rather to the cooperative interaction of multiple oxidation states on the surface of the iridium oxide that of course there may also be some effects of change and of entropy associated with a change of potential. But what's maybe more striking is that the molecular system shows reactor kinetics which are entirely independent of potential. The flux is changing of course because the density of oxidized species is changing but each but the actual reactor kinetics are independent of a degree of oxidation of these molecular clusters because of course these molecular clusters are all behaving independently. So there's no cooperativity between different iridium centers beyond the simple iridium dimer. What this means is that the molecular system actually is rather faster at oxidizing water at low oxidation densities when the iridium oxide system that the individual iridiums find a hard job to find each other and behave cooperatively. But at higher potentials with the iridium oxide heterogeneous system actually has a higher turn of the frequency or reaction time compared to molecular system most likely because of these cooperative effects. That was the end of what I wanted to talk about. I can see I'm going to run out of time quite soon. I'd like to thank everyone who's been involved in this work for my own group in particular. I hope I showed you various names that are key people involved during my talk particular Carlotta and Reshma and also Sasha and Lyon, Florian and Camillo and Ernesto I particularly talked about. I'd also particularly like to thank the many people involved in collaborating with us on this work and this includes people like Victor who says his calculations, Michael, Qunshin, Julio, Gary and Dunway and Andreas, the samples, Eiffen for helping us to understand electric catalysis and SIXTO for some of the analysis of impedance analysis and also some of the samples we've been looking at. I'll finish with a summary. I hope I've given you some idea of doing optical spectroelectric chemistry which is essentially putting your electrode in a UVV spectrometer and measuring the absorbance as a function of potential or as a function of light irradiation and in practice to get good signal noise we design our own spectrometers to do this. This gives us a complementary handle to electrochemical measurements of current density and it allows us quite easily to quantify how rates of reaction change with population density. It doesn't give us much information on the electronic nature of the states of the UVV spectra typically rather broad and featureless and there are far better techniques to measure or per handle the nature of accumulated species whether it's Raman or infrared or X-ray absorbance but in terms of just measuring populations versus light intensity or potential then this rather simple measurement can be quite powerful. It helps us think about when we are driving reactions whether the key thing with the limiting the rate of reaction is the accumulation of that population or the chemistry, the catalysis, the rate determining step. For most of the systems we've studied it looks like the kinetics often appear to follow something close to a rate law behavior. In other words, something which appears more like a population rather than a bottle of Olma to the kinetics. In other words, that the reaction changes as a function of light intensity or potential not because we are changing the energetics of the states for enthalpy but because we're changing the density of the states of entropy. We are seeing in our measurements I didn't talk about it yet because we're still working on that but we see deviations of population behavior particularly when we go to very high charge densities and that's most likely because then we are indeed hitting behavior which is more bottle of Olma like where as we go to very high surface oxidations then the rate therefore flux of reaction is no longer controlled by the population but by shifts in the enthalpy as you imply a deeper potential or you accumulate more charge. And I hope I've given you some idea that by measuring these sorts of rate laws we can get some insights into reaction mechanism and with that I think I should stop and I hope that you found that useful Olma and interesting, thank you. Thank you very much James. So we are all clapping even if you cannot really hear it and obviously yes, we found it very useful to have the experimentalist's perspective especially for theorists, this is always very good. So I invite everyone to ask questions in the Q&A and I would like to abuse my power of a jamming to ask the first question myself and in the hematite system you have been talking about these all important holes at the surface what are these iron four ions or does one know somehow where the holes reside on which ions and something about these? There's been some FKIR studies which are particularly by Thomas Hammann which would suggest that the surface holes are iron four oxos. Okay. And when we look at the different spectra as a function of whole accumulation then we essentially just see one species accumulating. So what we imagine is that we're increasing the density of iron four oxos on the surface. I see, but there is no direct experimental evidence or something. No, so Thomas Hammann had FKIR analysis which directly suggested that the states accumulating on the surface are involved in iron four oxo bond. Okay, very good. So then I would like that some of the participants can ask questions and we start with the Prazenjit Ghosh who has one question you should now be allowed to talk. Am I audible? Yes. And can you please first say your affiliation and then ask me questions? Okay, I am Prazenjit Ghosh from Indian Institute of Science Education and Research Pune in India. So my question is... I can see the question in the Q&A if that helps. Yes. Yeah, but for everyone because only panelists I think can see the question. Oh, I see. So particularly for the cases where it involves breaking up a OH bond or say two hydrogen atoms combining together to form hydrogen. Shall I answer the question anyhow? Sorry? Hello, James, did you hear Prazenjit who was... No, I didn't hear him. Ah, okay. Can you hear me now? Okay, there seems to be an audio. We can hear the Prazenjit Ghosh. You cannot. Yeah, can you just answer the question then perhaps from we? I think the question is how important our proton tunneling effects. Exactly, yes. I don't know. If you want to accumulate multiple oxidizing states all in one place, then if those states are all charged, then they would repel. And so it's very difficult to accumulate multiple oxidations in one place without some mechanism of achieving charge neutrality. And the most obvious way of doing that is by having proton-coupled electron transfer, the idea that when you put holes on the surface of hematite are associated with our leased protons. And that certainly fits with calculations from Victor Batista, which would support the idea that the oxidations on the surface are associated with proton release. It's consistent with that assignment to an iron-4 oxo where we've probably gone from an iron-3 OH to an iron-4-0 and there's a proton released. If you want those iron-4 oxo to diffuse across the surface in order to accumulate it at a site, then every time they move, the proton's got to move as well. And so understanding the proton dynamics on the surface will be, I imagine, very important for the diffusion of holes at the surface. And our pH data, which suggests that for a rate constant for water oxidation changes, it slows down when you start to change the protonation of the surface, suggests that may be the case. I'm not quite sure if that's what you meant by proton-tunneling, but we've got no direct evidence or measurement of proton-tunneling, but I think our data will be consistent with at least proton-coupled electron transfer being important for how holes move across an oxide surface. Okay, thank you very much. And let's make one more attempt, Jose Carlos Conesa. Can you try to unmute yourself? Yeah. Okay, so can you say your affiliation and ask your question? I belong to the Institute of Catalysis and Pedrology. I can't hear anything. And the question is for Dr. Darran, how do you measure the surface concentration of holes or hematite or an iron-doped nickel-oxyhydroxide? Okay, so James, since you cannot hear it, the question which you can read, it's about the measure of the surface concentration of holes in hematite or iron-doped. So all the measurements we do are based upon measurement of an optical signal, and then using the Bialambut law to turn that optical signal into a charge density. Yes, but the- In principle, it's very simple. Of course, the hard bit is to make sure that the optical signal you're observing comes from the states you're interested in. In hematite, we've spent years looking at the spectroscopy of hematite photoelectrodes to understand and have understood that on the time scales we're measuring, the only things which live long enough to give rise to optical signals on seconds time scales are holes which accumulate in the space charge layer of a hematite surface. And so in the electric catalysts, then the hard thing is that there's multiple redox states of many of these electric catalysts and working out which optical signal corresponds to the states which are driving with the water-oxidation chemistry is actually most of the work. But it essentially is Bialambut law to turn an optical signal into a concentration. But then- Yeah, but then- I think there's a point Jose that you asked about because Professor Doran cannot hear you for some technical problem. So let's try Simone, you had the question. Perhaps I hope that you can be heard. Well, my main question is just which spectroscopy optical or any other type do you use for this measurement? Okay, so James, probably you didn't hear it. No, I didn't hear anything. I don't know why I'm not hearing it. Yeah, Jose, he asks which kind of spectroscopy, so which concrete technique would you use to measure with the density? Which kind of spectroscopy, yeah. Just UVVs near our spectroscopy. So many measurements we do, you can do with the UVVs of spectrometry you'll find in most undergraded teaching labs. Okay, Simone, yes. Yeah, well, I have several questions, but let's start from the very last that was asked by one of the participants. So is it always the case that the signal and the concentration of the holes are linearly related? So throughout the range of concentrations or signal that you measure, is it clear, is it obvious that the two are linearly related? As far as I'm aware, the Beard-Lambert law is based upon the idea that a concentration of species is proportional to an optical signal change. Does it hold at all concentrations or does it break down in the high concentration limit or in the low concentration limit? I'm not sure. The Beard-Lambert law is designed to, if you measured only light transmission intensity versus concentration, then it breaks down. Which is why the Beard-Lambert law uses a logarithmic measurement of the change in transmission to calculate the optical density. And so the measurements we do essentially, the way the optical density is defined is defined to be linear in concentration. We haven't gone to a very high optical densities, you get problems, but we're not in that limit. We're typically in the limit of quite small optical signals where we expect the best linearity. Okay, okay, thanks. And not related to this, but again on the experimental side of the measurements. So I've seen several papers in which the effect of the pH has been reported. And as far as I can tell, I'm a theoretician, so I cannot judge the quality of the experiments, of course, but different papers report different findings. So some of them have in the title the effect of the pH on the turnover frequency on hematite. So I guess you might be aware of these conflicting reports. So can you comment on this? So you have shown that there is basically no pH effect up to the point of the point of zero charge. And then above that, there is a behavior that is not easy to interpret, let's say. Whereas other reports are quite different and they support the notion that at alkaline pH, it is the hydroxo taking part in the reaction. So can you comment on this? We have observed changes in mechanism of reaction of pH in some oxides. And so for example, in titanium, we've observed that it's third order at alkaline pH and second order at a lower pH, just in the change of reaction mechanism. We've only looked at one hematite so far to look at the pH dependence. I'm aware that if we had analyzed the data as a rate versus pH, rather than a rate constant versus pH, we'd have got quite a different answer. And we certainly see big effects of pH on the generation of holes at the surface, on the space charge layer and this sort of thing. And so it's very important to, we only see a rather pH-independent behavior when we are plotting the data versus the accumulated charge density and affect the calculated rate constant, not a rate. But I wouldn't say we've done, we've only done one study so far on one hematite and when we've compared to, I wouldn't want to say more than that for now. I don't have a, I can't explain anything. I'm sorry. Thank you. Okay, so I would like to give also the floor again to someone from the participants. James, since you cannot hear them, perhaps say you can just read the question by Duitain Bouyen, do you think that the oxygen in iron oxide joins to the oxidation process of our water molecule, which can affect the order of the reaction? Certainly there's quite a lot of discussion with in some electric catalysts that oxygen in the material may be involved in water oxidation. The model which Victor has from the DFT calculations would indicate that it's only the surface-ligated oxygens which would be involved in the water oxidation and plus water, plus water, of course. So I guess not, but I wouldn't say I'm a world expert on that. Okay, you had some questions in some time, please. Yeah, thank you. Thank James for the very interesting talk. Of course, you show very strong evidence that the tunnel frequency rate is actually very low. You show you have really a couple or three holes accumulate together, really concentrate at a very small thing near the same one or two sites. I would expect that will cause a huge distortion in the local structure. So can you give, so what can you say something about what you would expect the structure look like? Has that something to do with, for example, in lots of the experimental evidence also show that the oxide undergoes strong dynamic change? I mean, the overall morphology, not just like a small change in a local site, but the whole structure can change your load. Do you have a relate to you that somehow? I had to be careful, because there's many things I'm not an expert on here, but all we are really saying is that we have water, the rate determining step of water oxidation involves, first of all, two neighboring iron centers becoming oxidized to run for oxoes. And so we have essentially a dimer of iron for oxoes, and then that dimer of iron for oxoes receives one further oxidation. Victor thinks that the most likely transition state involves an iron five. It may also be for the third oxidation is actually one of the options or the service like getting water. So I don't think it's so extreme. It's not so different from just the idea that you put a whole of a surface of hematite and you get an iron for oxoes. Okay, I see, okay. Can you see what I mean? Yeah, yeah, you mean basically structure really maintains overall frame? Obviously, I don't know, but I don't think that there has to be a large structural change in order to explain what we observe. Okay, okay, thank you. Okay, so let me ask one last question from the participants by Navit Hagmuradi. He asks, do you think that the interaction of electromagnetic waves with the water molecules, which are obviously polar, can change their adsorption on the photocatalysis surface and therefore somehow the reaction? We can observe for water or oxidation kinetics different ways. And one way is under continuous irradiation where we observe a charge density as a function of light intensity. But we can also measure the kinetics when we just turn the light off and go to open circuit and measure the decay of those holes at the surface with no light irradiation present. And again, we can measure water or station kinetics when the kinetics measured essentially in the dark, just allowing the surface holes to react to make water are identical to those measured under irradiation from their population density and current density. And so as far as we can see, the presence of light has no impact directly on the kinetics. Okay, so let's finish this thing with one question from Tanja Cook who has one quick question, the quick answer, please. Okay, so I was interested in the... Thanks for the great talk. I was interested in the terminal frequency versus charge density where you were comparing different materials, the generality of the results. Oh, yeah. TIO2, there's the besmith vanadium oxide and then there's the iron oxide. And when I look at the original paper on iron oxide, the way you relate these on the X-axis is through light fluence. So you take the light fluence, you change the charge, and then that changes also the current. So in the iron oxide, what I see from the initial paper is it's a 60% efficiency of light to charge overall. But if I look at the TIO2 papers and the besmith vanadium oxide papers, it's much, much lower, it's two to 3%. And so I was wondering, first of all, why is that experimentally? Why is one such high quantum efficiency one low? And does it matter for the results? Does it matter for these types of plots? So I think the high quantum efficiency for the hematite was because that was Michael's fancy nanocoloflars whilst for things like BVO data we showed, that was typically not particularly high performing flat BVO electrodes. We've calculated for water oxidation rate constant on different hematites with different morphologies and different quantum efficiencies. And when we, so this was, we've gone from flat to, and different needing temperatures and all this sort of thing, and also different defect densities. And when we overlay and calculate the rate constant, then the rate, of course, then you get very different hole densities for the same light flux because the quantum efficiency is different and all this sort of thing. But when you analyze the rate constant from the surface hole density versus water oxidation, then they're all the same. Interesting. So I think that it's not a rate constant of the flux is as far as we can judge, just controlled by how many holes you accumulate independent of the quantum efficiency of the system. Okay, thank you. Okay, that's what we see. So there are still some open questions, but I think we should close here because we are nearly a quarter of an hour behind time already. Sorry, sorry, sorry. Thank you very, very much again, James, for this very nice... That's my pleasure. Thank you for all the questions. Yes, I'm sure we could go on still for half an hour with questions. Okay, okay, so... I think my zoom is crashed, so I'm gonna disappear and restart. Okay, yeah. If you can un-share the screen before. Okay, so here we are. So the last talk of today is given by Francesca Tomer. Francesca is a staff scientist at the Lawrence Berkeley National Lab and working there in the Joint Center for Artificial Photosynthesis. Her specialties are a synthesis and characterization of these materials, which are interesting for us this whole week. And here is someone speaking from Isdbeen Trieste. It is also nice to mention that Francesca, before becoming a Californian, she was here in Trieste for several years, both at CISA and at the University of Trieste. So basically a neighbor of us. Francesca, can you try to share your screen? Yes, I'm trying, just one second. We see and hear you, but so far no screen. Okay. You should see my screen now. Well, yeah, now it is here. Okay, I'm not taking full screen mode, but we can see the power point. Is it in full screen now? Now it is in full screen. Very nice. With a double face, very good. Okay, so Francesca will talk about photo-electro-catalysts at work. Okay, please. Thank you, Ralph, and thank you for the nice introduction. It is indeed a pleasure to present at this workshop. I have been, my very first conference was an ICTP conference, so it's really a pleasure to be here. And I wish we could do this in person and hopefully we'll meet each other, if not next year and very soon. So yes, I have the Janus two faces here because part of my talk will focus on durability. A lot of the research that is going on in this field and we heard some questions just now from Tanya about quantum efficiency and efficiency of this material, which is certainly important. But as I will show today, also durability, it's an important characteristic that materials for solar fuels should have and probably something that we should start focusing more and more going forward, especially if we want to become more sustainable. So on this note, myself and a lot of people in our community are driven by is the energy problem and climate change. We have increasing level of carbon dioxide that are causing increase of global temperature, decrease of arctic ice minimum and ice sheets and increase of sea level. All of this, as we well know, is the cause of climate change. And it's really interesting to me how the United Nations are looking at this problem and they have together with different governments, they put together an agenda with 17 different goals and the goal number seven is on affordable and clean energy. And really what they ask us to do, this is how I interpret this, is to increase the share of renewable energy but do so by increasing international cooperation. So that's why conferences like this are really important to have people talking to each other and really go beyond the boundaries of what one single group can do and try to collaborate together and come together to a solution. And again on this note, I will add that probably the solution will not just be one single type of renewable energy, but a combination of these. These are solar and wind batteries and electrolysis, carbon dioxide reduction, carbon dioxide capture. And depending on where you are on the planet, basically any one of these alternatives could be a perfectly fine alternative that we can use. Specifically today, I'm going to focus on solar fuels productions and I want to compare solar fuels and just give some more motivation on why it's important to work on solar fuels with respect to batteries, for example. So first of all, the price of solar power models is decreasing and it's now about 0.5 US dollars per watts. And we are on track with what the Department of Energy has set as the goal for the residential solar power by 2030. In addition to that, one would also want to consider that high energy is crucial for electric vehicles with batteries and stability is also another crucial parameter for the grid storage. And so in this scenario, in this perspective, solar and chemicals fuels are a convenient way to store electricity because their volumetric and grammatical density outperform those one of batteries. And we see this in this graph here in which you have volumetric density and you have a specific energy density, so grammatical density. And you see that hydrogen is, for example, on the, as a high, as a, is on the side of the graph. And solar fuels are very similar to fossil fuels in a way and are on the more central part of the graph. And lithium ion batteries that are basically existing batteries are instead on the lower part of the graph. So have perform worse with respect to what could, what hydrogen and other solar fuels could do. At Ralph mentioned earlier, we, I work at the Joint Center for Artificial Photosynthesis or better the Joint Center for Artificial Photosynthesis is coming to an end by the end of this year. And it has been a collaboration between different centers, the research center where I work at the National Lab, Caltech, UC San Diego, UC Irvine and Slack. And recently we were awarded a new grant, so called the LISA Liquid Satellite Alliance, also together with the same university. And in addition to that, the National Renewable Energy Labs and the University of Oregon.  So in the first five years of the Joint Center for Artificial Photosynthesis, we really focused on hydrogen generators and how to make hydrogen utilizing sunlight. Whereas in the second phase of J-CAP and even more going forward with the Liquid Satellite Alliance we have been focusing on CO2 reduction in the second phase of J-CAP based mainly on electro catalyst. But then going forward really we will focus on how to utilize sunlight to reduce carbon dioxide to possible solar fuels. So I want to show here a device that we realized at the end of the so-called J-CAP one. And this is a hydrogen generator in which we have a three, five hydro junctions with a catalyst on top. You'll see the light going off and then, sorry. Light is going off just right now and then you see bubbles and these are hydrogen bubbles that are originated from the water splitting reaction. This device was performing at a conversion efficiency of 11.3% which is about 10 times higher than what natural photosynthesis does. So when we want to make an integrated solar to solar to hydrogen generator or solar to fuels generator as the one that I just show, there are different components that needs to go in this device. Catalysts are on the interface between the electrode and the electrolyte and they are aiding the reaction either oxygen-evolving reaction or hydrogen-evolving reaction or CO2 reduction. Then we have light absorbers that are absorbing light at the oxidation side. We have the photo anode at the reduction side. We have the photocathode and then we have interfaces between all of these different contacts. So when we want to design a device that is efficient and stable, we need to think about all these different components and we need to optimize their interfaces. And this is what I do with my research group. We look at those different problems making integrated solar to fuels devices and looking at components, but also integration. And for doing so, we look at interface engineering for solar to chemical transformations. We have a collaboration with the Hydropod experimentation group in Caltech. And we tried to do direct catalyst discovery on top of light absorbers and direct discovery of optimized interfaces in this way. This is that you see here a plate, a 10 by 10 centimeter square plate of bismuth monodate where there's several tiny spots of catalyst that have been deposited on top and that can be analyzed with a droplet cell. We also do scanning probe microscopes to characterize these materials from a functional point of view as I will show later in my talk. And we also look, as I mentioned earlier at electrochemical CO2 reduction and also at light-driven CO2 reduction. So today specifically, I will focus on more details on how we think about the integration of solar to fuels devices. And then I will talk about the importance of local environments to drive chemical reactions with specificity for electrochemical CO2 carbon dioxide reduction. So going a little bit more into the energetics of artificial photosynthesis, which as I mentioned before is the analogous, the man-made analogous of natural photosynthesis. We look at light absorbers that are interfaces with each other. And we have a photo anode where minority carriers are holes that are taking care of the oxidation of water into oxygen. And then we have a photo cathode at the reduction side where minority carriers in this case are electrons that are at the surface and reduce water to hydrogen. The energy requirements specifically for water splitting reduction are 1.23 volts, which is the thermodynamic potential that we needed to split water. But in addition to that, we have also a kinetic potential that we need to consider, which takes our total potential to 1.7 volts that it's needed when you have the semi-oxidation reduction and the semi-oxidation, sorry, the semi-oxidation reaction and the semi-reduction reactions. So what we want from our light absorbers is that when you shine light on them, the photo voltage that you can get out from the photo cathode and the photo anode combine is at least, if not more than 1.7 volts. And that's why we're interested in photo anodes or photo cathodes that can give us a high photo voltage. On the photo anode side, one of such materials is Bismuth Vanadate. The Bismuth Vanadate has a band gap in the visible range so it can absorb sunlight and has a very high photo voltage of about one volt sometimes even more. It has a sustainable valence band for water oxidation. And when we started studying these materials five to six years ago, at the time the material was reported to be stable as a metal oxide performing water oxidation. So we work first on trying to improve the performance of this material. As I said at the beginning, performance efficiency is really something that needs to be there for these materials. And in order to do so, we took Bismuth Vanadate and we doped it with molybdenum. We made such as those big slides just because of sputtering, but also other deposition techniques such as spin coating can allow you for really high homogenous and larger air devices. And this is how the Bismuth Vanadate photo electrode appear at the scanning electron microscope. So it has a grain size distribution. It's a polycrystalline material. Once we do characterization, we fabricate our photo electrodes that look like so and we can test our photo electrodes in the photo electrochemical cells.  We have a counter-electrode which is usually plotted on the reference electrode which is silver silver chloride. And then we test our performance in a buffer. There can be different buffers. We usually use phosphate buffers for this material. Here you see the performance with the linear simple tomograms. It's current versus potential. The blue line here is the performance of the material that is undoped so without any molybdenum. But then when you doped the material you see how the performance is really increasing. And if we look at about 1.23 volts versus RHE which is what we identify as the thermodynamic potential for water splitting, you see that you have current density of about four volts between 3.5 and four volts, sorry, medium per centimeter square. In addition to that the answer potential is also increasing which is the parameter that we care about when we look at the photo voltage for the material. So we proved that the material could be made scalable and reproducibly. And we also were able to improve the performance. So when you're making a solar to fuse generator then in addition to performance you want that to be stable. And at least at a lab scale measure stability we need something that is stable for at least 100 hours. So this was very disappointing because when we tried to run the stability of this material for a prolonged period of time immediately already after one hour in pH near neutral the stability of the material just degrades over time. And the situation is even worse when you have an alkaline pH, so a 12.3. Here I reported in this blue dashed line what the stability, the ideal stability should be like. And this is a normalized photo current as a function of time. And this was what happening to the material over time at the scanning electron microscopes. So as the positive material as I showed earlier is a very nice grain size material and grains were fusing together already after 60 minutes at pH 6.8. And after 20 minutes grains were basically disappearing and what you see here in this bluish is the underlying substrate which is fluorine doptinoxide. So we did some chemical analysis and also analyzed more in detail the origin of this degradation process. So for chemical analysis what we looked at was the electrolyte. We analyzed the electrolyte by elemental analysis ICP a mass spectrometry. And we looked at the concentration of vanadium and bismuth in the solution as a function of different conditions. Light versus dark and different potentials and the different pHs of the electrolyte. So this dash blue line is the thickness of the starting bismuth vanadate between 15 and 16 nanometers. And you see down here the etched thickness of the material. And so do you see my mouse by any chance? You do. Okay, actually let me use the pointer maybe so it's better. So this darker colors the blue indicates the vanadium and the red the bismuth. You see when you shine light the degradation is higher to with respect when you don't have any light shine and there's the more transparent color. And in addition to that the potential has also a role. Here we are at open circuit potential and here we are at the thermodynamic potential for water splitting at 1.23 volt versus RHG both at near neutral pH. And then when you increase the pH as you noticed earlier the degradation is even higher. And of course again this depends on the potential. And so literally we can say that the gradation depends on light increasing pH values applied bias and also concentration of the electrolyte that you use. So we correlated this with what was reported for thermodynamic stability of materials. So I showed earlier this diagram for both photocatode and photoanode. Here we are focusing on the photoanode side. When you shine light on a material you have a whole and electron generation and charge separation and the hose will go to the surface with this upward bending diagram and the electrons will go to the photocatode. And the hose will oxidize water. This is in the ideal case. But then what we are not considering is the self oxidation of the material itself. And depending of where the self oxidation level sit with respect to the oxidation potential of water then we'll have an equilibrium of these holes that can go and oxidize water or oxidize the material itself. And this is again from a thermodynamic perspective. So Lingwen Wang and his collaborators made this very nice diagram with different materials. The water oxidation potential and the water reduction potential up here and valence band and conduction bands and the self oxidation and self reduction potentials. So self oxidation potential are indicating here in red and self reduction potential are indicated here in black. So let's focus on the Bismuth Vanadate which is the material under analysis. Here you see the valence band of Bismuth Vanadate and the self oxidation potential which is indeed very close to the oxidation potential of water. So you could already argue that under the water splitting conditions Bismuth Vanadate would have an equilibrium of holes that can either oxidize water or oxidize the material itself. And so the material should not be stable which is a reasonable argument. But if you consider this with the hematite which I'm sure James just talked about, you'll see that hematite is actually in a very similar conditions. Yet hematite is really very stable and does not be great under water splitting conditions. So something more it's going on and instability cannot be described only using by thermodynamic arguments. So we collaborated with Christine Persson and the materials project team to look at what could happen at BVO, a Bismuth Vanadate if you look at the poor bed diagram. The poor bed diagram is a phase diagram that inform you on the possible different phases that are stable in different conditions of pH and of potential. This is the, in red, the window of stability of Bismuth Vanadate at different pHs and a different potential. And these are all the different phases that are stable otherwise. And here dotted in red, you see the oxidation potential of water at different pHs. So you see that Bismuth Vanadate is sequentially never stable when you perform water oxidation. And what should happen is that a Bismuth oxide solid should form on the surface of Bismuth Vanadate. Well, with our chemical analysis, we already knew that that was not, was going on. And we knew that we were not forming a Bismuth Vanadate also, sorry, we were not forming Bismuth oxide also from X-ray photoelectron spectroscopy measurements that I'm not showing here. So we gave this feedback to the material project that was able to prevent the deformation of this solid, Bismuth oxide solid. And if they do that, they can predict a redefine property diagram in which you have oxide Bismuth hydroxide ions together with Vanadate ions or this Bismuth oxide plus ion together with Vanadate ions. So we investigated even more the degradation, the mechanism of degradation with the electrochemical atomic force microscopy. And we look at how at the nano scale, the materials changes over time to get even more insights into the corrosion mechanism. And at the same time with photo-conductive atomic force microscopy, we also looked at the nano scale of the electronic properties of the material. So electrochemical atomic force microscopy is let's say a miniaturized electrochemical cell in which you have an atomic force microscopy probe that is scanning on top of your photoelectron. And you can apply voltage on your electrode and the solution, you can also have counter electrode and reference electrode. So if you look at the real-time transformation with electrochemical atomic force microscopy, what you can see is that you have a dissolution process of Bismuth Vanadate, which confirm exactly what the redefined pure bed diagram was predicting that the material is actually dissolving under operating conditions. And this degradation we found out so from statistical analysis starts at the solid-liquid interface. And you can see this from this video here, you'll see the material etching away and you can focus on different areas, this video goes in loop so you can see it now, it starts again and you see that, let me, I think it stopped. Okay, you can see that the material is etching, which is also confirming the original scanning electron microscopy image that I show you in which you have these grains that first starts using together and then they actually dissolve faster at a higher pH. So we can do even more analysis to delve deeper into this mechanism of corrosion and really understand what's happening at the nanoscale and how functional properties are changing and how chemical heterogeneity can also affect stability of the material. We did this with two techniques, one I'm going to talk about right now, photoconductive atomic force microscopy and another one is scanning X-ray transmission microscopy. So in photoconductive atomic force microscopy, we have a laser that is a shining light on a sample from the bottom and then we have a conductive probe and we apply a bias on our sample. And if we scan our probe, we can collect the current maps and if we instead leave our probe onto the sample, we can collect IV curves. And we are basically analyzing the circuit between the substrate, the Pismuth validate and the probe itself. We can measure current when applying a bias under dark and specifically we saw spots that were related to shunts between the tip and the fluorine-optin oxide underline the substrate. And then we can shine light at different wavelengths below the band gap and above the band gap to understand whether defect states are contributing to generation of the photocurrent. And what we can conclude from here is that there are not very many defect states that are contributing to generation of photocurrent for business validate. We can do again statistical analysis to understand whether we have artifacts of the tip. Here I'm just reporting an example in which we demonstrate that average photocurrent is not dependent on the green size. Once we know that we are not dominated by artifacts by the tip, we can perform a more statistical analysis and understand the current of the heterogeneity in the photocurrent. Specifically for this material, we noticed that we have three different regions. One are the grain boundaries, one are the facet planes and one are the facet boundaries. And we noticed that the higher photocurrent is generated at the facet boundaries. And the fact that we do not have a lot of photocurrent generating at the grain boundaries also is another proof of the indication that business validate is defect tolerant. Something else that we can do with this technique is actually understanding the dominating charge transport mechanism of the material by looking at IV curves and by studying the high bias regime the relationship between the current and the voltage. By looking at the log log plot, we see that we have a power load dependence from of the photocurrent with the voltage. And if we change the intensity of the light that we are using or we change the temperature that we're using, we can get even more information about the characteristic crossover voltage. And we can find out what's the actual mechanism of transport, which in this case, it's a bulk limited transport mechanism a space search limited transport, which means that electrons are limiting the properties of the material of the specimen metadata. So this technique allows us to provide the functional information, but yet doesn't allow us to provide chemical information. And we did that by looking at the scanning transmission X-ray microscopy, which is a technique that allow us to resolve specially the electronic and the chemical structure of materials with a lateral resolution of about 20 nanometers. So basically you obtain energy filter images and from the images, you can get X-ray absorption spectra at different edges. And the one that are of interest to us are the monadium edge and the oxygen edge. This is a schema of the beam line that we used at the advanced light source. And then we did more studies to analyze these results and find a few information about our samples. So specifically we compared our sticks on our scanning transmission X-ray microscopy images of the S-grown and the graded samples with the atomic force microscopy images. And we found that we have two regions that are different in these images, the grain boundaries and indicating in blue and the grain centers indicated in black. So in collaboration with David Prendergast and Sebastian Reyes-Rilo, we perform also some calculation to have a better interpretation of these spectra of this X-ray absorption spectra. We first perform principle component analysis to help infer the main spectral components in this spectra and confirm that we indeed have these two different components on the grain center and the grain edge. And then we analyze better these components to understand the origin of these differences. And what we found specifically is that we have an accumulation of vanadium oxide at grain boundaries. And you can see this by differences in the vanadium L regions and in the oxygen K edge region. And especially from comparison between the S-grown and the graded samples. And if you compare this vanadium oxide presence to the overall argument about this with vanity corrosion and how this corrosion starts from the solid liquid interface, then you can understand how possibly an ounce presence of vanadium oxide at grain boundaries can aid to increase corrosion. I also want to show another example of how we use the different techniques to characterize stability of materials and transformation of materials. This is the case of photocatode, a silicon-based photocatode covered with a layer of gallium nitrate. We notice in this case that by the linear simple tomogram, we have an increase in the photocatode over time and an increase in the onset potential over time.  The first analysis we did in this case was X-ray photoelectroscopy of the pristine material in which we have, this is the oxygen 1S peak, we have gallium oxide, the component, and the hydroxyl group due to the absorption of water. And already once we start running the chronometry, we see that after one hour, we have the presence of a new peak, an oxygen nitride gallium peak. And this component keeps increasing over time after four hours and while the gallium oxide component goes down and this growth of this component reaches a plateau after four hours. So if we look again at the photoconductive atomic force microscopy measurement for the silicon gallium nitride photocatode, what we see here, and we're just shining light on the sample and measuring photocurrent without any applied bias. We see that we measure a photocurrent in the order of peak on pair for the pristine material. But then when we shine light on the reacted material, so we take the material after 10 hours of chronometry, we see that we have an increase in the photocurrent to non-on pair. So we have three orders of magnitude increase in our photocurrent that is specifically localized, especially at grain boundaries in this case. So we did some STEM analysis, so scanning transmission electron microscopy and we look at the N, the nitrogen K edge, the gallium L edge and the oxygen K edge of the pristine material and of the material after the text. So if you look at the pristine material, you see that you have nitrogen and gallium that are co-localized but no oxygen. On the sidewalls, you still see oxygen on the top surface of the gallium nitride. And then the situation is different when you run the material and you notice that you have nitrogen and oxygen that in this case are co-localized with also gallium. And this supported our hypothesis that we are indeed able to originate this new component of gallium oxynitride at sidewalls. And this increase of gallium oxynitride sidewalls is in line with the increase, the overall increase of the photo current at sidewalls that I just showed with the photoconductive atomic first microscopy. So I hope that I still have some time to go through the last slides of my talk about how we look at micro-environments for CO2 reduction, is that okay? Yeah, sure, it's okay, yes. Perfect. So I want to briefly move the focus on a different problem. So right now we really looked at hydrogen generation in the last part of my talk, I want to focus on CO2 reduction. CO2 reduction is a whole different beast in terms of thermodynamic and kinetics challenges because we need way more energy to reduce carbon dioxide to fuels that are also specifically relevant if we want to have a high energy density. And interestingly, one of the main metal that is active towards CO2 reduction is copper and on copper we can make up to 16 different products which again, increase the challenges of these reactions. And so as you see here, you have depending on how many electrons are involved in the process, all these different products. So what we want to do in CO2 reduction is focusing on selectivity of the reaction and also on the efficiency. So basically we want to reduce the number of products that we can make and we want to make them in large quantities. Also in this case, we take inspiration from nature and nature has an enzyme that take care of this reaction in natural photosynthesis, the rubisco. Rubisco operates in dark and it's the enzyme that is responsible for the CO2 fixation. What's special to us about this enzyme and it's similar like if you look at the enzyme work, all enzymes work like that. They have a catalytic center but this catalytic center is surrounded by a series of amino acids and sometimes some metal supported atoms that are making that environment special and are making that environment selective. So with this in mind, we have different ways that we can address selectivity. So one is the catalyst composition. Another one is the catalyst morphology by looking at different morphology. We can also somehow drive selectivity. Simone earlier on asked a question about pH. pH also happens to be very important in CO2 reduction and determining the selectivity in CO2 reduction. The electrolyte is another parameters. The applied potential of course and another important parameter is the utilization of supporters and organic modifiers that you can use locally to change your environment. So in this case, we used different organic modifiers. I'll show the structure in just a minute. We took a copper foil and we made it more active by oxidizing it. So basically we made the surface rougher and we introduced the presence of more oxygen atoms that are making the oxide derived copper more active towards higher hydrocarbons. And then we functionalized the copper with different organic modifiers. And these organic modifiers has different structure characteristics that we could map onto to understand the selectivity towards specifically three different products. Hydrogen, CO, and formic acids. So we operated to focus on these three products. We operated at low potential on copper surfaces. And here you see three different structures, specifically this polyvinyl pyrrolidin, this hexadexel ammonium salt and this amino derivative. So what you can already see from these bar graphs, on the left you have the product distribution of oxide derived copper. And then you can see that when you have a product species you have an increase of formic acid. And when you have product species you have an increase of hydrogen. And the situation is different because when you have alkyl ammonium salts. And I will show in just a moment how the situation can be different when you have ammonium salts and in general, heteroatoms. You see here that when compared with oxide derived copper when you have ammonium salts you can vary the selectivity between formic acid and the carbon monoxide very selectively in this dihexadexyl dimethyl group case and in this dihexyl dimethyl group case. So looking specifically at this different product distribution of these two molecules we collaborated with Tao Cheng and Bill Goddard and look more in detail at what was special about these two molecules. So first we run an experiment to look at the role of water and to understand how hydrophilicity was specifically different between the different structures. And what you can see here is indeed these different structures are different from an hydrophilic hydrophobic point of view. And you can see that more hydrophilic structures reported here on the left are giving you more formic acid and more hydrophobic structures are giving more CO, carbon monoxide. Which is the precursor to higher hydrocarbon. So that's why we're interested in carbon monoxide specifically. And as I said, looking at force field simulation we can understand the role of water and we can look at the very first layer at the very interface between the water and simulated interface between copper and the modifier both the more hydrophilic modifier and the hydrophobic modifier. And so in this graph here you can see the water density distribution as a function of the Z axis. And you can see that indeed when you have a more hydrophilic modifier you have more water. And when you have more and more hydrophobic modifier you have less water at the very interface between the modifier and the copper surface. And this content in water is indeed important because it determines the mechanism of CO2 reduction towards carbon monoxide and towards a formic acid. So Tao Cheng and Bill Goddard also stimulated the energetics between the production of formic acid with the two different modifiers. And what they confirm by simulating the energetics is that indeed the production of formic acid is facilitated on a surface with an hydrophilic modifier. So lastly I want to show that not only water is important in determining reactivity and selectivity of these surfaces but also the distribution of carbon dioxide at the surface. Specifically, we focused on silver that is very well known to promote selectively carbon monoxide production at higher potentials. And we looked in this case at low potential where the production, I apologize, there is no scale here a color scale to understand that the gray is the hydrogen and the red is the carbon monoxide. You see that the low potential we are a minus point eight volt versus RHE on silver. You have a lot of hydrogen that is produced but when you have your modifiers in this case that we have one C16 which is a trimetal diaxadecil substitute to the ammonium salt and then you have diaxadecil dimethyl ammonium salt and then you have two chains with the C10s and one chain with the C10s. You see the different product distribution. And interestingly, when you have two diaxadecil chains you see that you just shift completely the selectivity from silver, from carbon monoxide to sorry, from hydrogen on silver to carbon monoxide on the modified surface. And we did some simulation to understand the distribution of carbon monoxide, sorry, of carbon dioxide at surfaces. And we see that indeed this specific modifier gives higher distribution and allows for a higher distribution of carbon dioxide on the surface of silver in this case. So just to conclude, I show how we use different techniques to characterize photoelectrons and integrated photoelectrons and how we understand the mechanism of transformation of photoelectrons at work. I show you how we engineer electrodes in this case but possibly also photoelectrons and how we change the local environment to drive selectivity and tune selectivity for CO2 reduction to hydrocarbon products. I want to acknowledge my group of course and my collaborators Ian Sharpe, Jason Cooper, Christine Person for the Bismuth Donate work, Dean Tost, Tao Cheng and Bill Goddard for the CO2 reduction work. And David Prendergast and Sebastian Reyes-Lillo for some of the work on the scanning Transmission X-ray Microscopy. Johanna Acorn perform a lot of the experiments together with Guijilio and the Bismuth Donate and Wilson Zeng did all the work on the gallium nitride silicon photocatode and Aya Buckley did the work on electro reduction of carbon dioxide. And of course the funding specifically the Joint Center for Artificial Photosynthesis. Thank you for your attention. Thank you very much Francesca. So we have already some questions here. Let me try, if this time it's possible to make the people who ask the question in fact speak that you can hear it. So one is by Fatima Matrodi, can you say something? Good afternoon. Hello, yes. Can you please say your affiliation and then ask your question? I'm an assistant professor in the Shah-e-Chamron University of Afoz, Iran. And I can hear you. You can. I can, yes. Yeah, that's good. Actually my question is about one of your, one of a part of your speak, you were speaking about some peaks. I think it was regarding these X-ray and you did the convolution for the peak. The peaks does not appear that much different but to create this third peak, actually it was a question in my mind how you realize that it should be also another peak regarding this nitrogen. We look specifically, sorry, maybe it's easier if I do like this. We look at vanadium and oxygen specifically and I agree with you. The changes are hard to appreciate and that's why we did some principle component analysis and then also we asked the help of David Prendergast and Sebastian Reyes-Lilo to perform some of the analysis and understanding of the spectra. So first of all, if you compare the S-grown material, you see my mouse, let me put the pointer. If you compare the S-grown material and the degraded material, you see that there is indeed a quite appreciable difference and you can look at the grain center of the S-grown and the degraded and you can look at the grain edge. And so specifically, and this was visible in one of the first images that I show, in the degraded material, which is indicated here in F, you have a higher component of the grain center just because of how the material degrades. It starts degrading at grain boundaries, envoys and you have a higher component of the grain center. And so by putting together all this information together with the principle component analysis information that really allowed us to see the difference between the grain center and the grain boundaries, we could see this presence of the vanadium oxide and the grain boundaries. So the main evidence for a presence of this nitrogen thing is this experiment, not the other one, yeah? It is this experiment. Yeah, and just for clarity, we are looking at oxygen in this case, not nitrogen. We have no nitrogen here. So I want to make sure that I'm actually responding to the correct question. I had nitrogen in this gallium nitride, for example. Was the scanning transmission electron microscopy that you were referring to? Yeah, yeah, exactly this, the past. Oh, the past one. Okay, so then no, we don't have any nitrogen, just for clarity. Actually here, yeah, for this deconvolution was my question, is how you realize that there should be another or this third peak that is oxygen nitrogen gallium? Yes, from the deconvolution of the, of the XPX spectrum. Yeah, but how you realize that it should be, and the third peak also not just only two peaks because the peaks are not that much different. And also the peaks actually very close to each other, they could be only two peaks also for the second one. If you fit the peak with just two peaks, the fitting, it's not good enough. So that's why we have a third peak and it becomes even more visible here. So when you have the component of all of gallium oxide that it's decreasing and you have the component for gallium oxide nitride that it's increasing. However, we have further evidence of this when we look at the scanning transmission electron microscopy image, you have on the sidewall, the collocalization of here in this case after the test, the collocalization of nitrogen and oxygen in the same area. Okay. Thank you. So this further is confirmed. Yeah, because this deconvolution was somehow questioning for me. So you saw some kind of asymmetric in your peak. So you realize that it should be another peak that is responsible for this asymmetric in your peak. Yeah. And some kind of shoulder thing is created. Exactly. So when you do the fitting with XPS or in general with the X-ray spectra, you can see, of course, I agree with you and maybe that's part of where your question is originating from. We could put five different peaks if we want here, right? And you can see sometimes that happening in literature, but in this case, if we only put two, the fitting is not good enough and you cannot fit well the parameters for the fitting are not good enough to justify the presence of only two peaks. However, if you add a third peak, then you can have a better fit. And you can also tell the software. Francesca, I think that was clear now because I would like to move on to other questions. Otherwise, because there's quite a series of questions. So next question is by Jose Conesa again from before. So if you unmute your microphone. Yes, my question is for Dr. Thomas. I belong to the Institute of Catalysis and Petroleum Chemistry of the CESIC in Madrid. And the question is, kinetics depends on overpotential. Which overpotential do you need to get 10 milliamps per square centimeter in water splitting? It depends on the material. So for Bismuth-Vanity, it will always be hard to get to 10 milliamps centimeter square. If you have three, five semiconductor materials that's of course easier to get there. And the very first example that I show was the first example that I showed was the first example that I showed was the first example that I showed was even above 10 milliamps centimeter square without applying a bias just having the three, five semiconductors at the junction and shining light. But this is with gallium nitride. Oh, the gallium nitride. So in this case, we're applying let me see. We were applying a minus 0.7 volt. So it's about minus seven volt versus arachid applied potential in this case. Okay. So then let's go to the question by Anish, PM. Can you unmute yourself please? Hello, we hear you. Thank you very much for the wonderful talk. My question is this. Say who you are, where you come from, please. Okay. My question is that in one of your initial slide you mentioned some molybdenum doping in Bismuth-Banai photorelectrode. And what is the reason for particularly selecting molybdenum in doping in Bismuth-Banai one is that it improves its electrical properties. However, more recent literature actually is talking about polar on conduction and it's also talking about polar on conduction. So, there are different theories about the role of molybdenum in doping in Bismuth-Banai one is that it improves its electrical properties. So, there are different theories about the role of molybdenum in polar on conduction in Bismuth-Banai specifically and in metal oxides more in general and how molybdenum can have a role into basically mitigating the effects of the polar on conduction in the material. So, that's becoming a more and more accredited work to understand how polarons can be seen from the X-ray fingerprint the X-ray absorption spectrum and we know that there is this role of polarons in the material and molybdenum specifically can help mitigating the effects of polarons in the material. Okay, is this okay? Thank you. Then there was one question by Deepak who we have already had before. Let me unmute you. Okay. Hi, I am Audevan. Yes, hello. We can hear you. Thank you for nice. Basically, I'm curious like the artificial photosynthesis you mentioned about the like convergent process on the carbon dioxide. So, do you focus on some other gases like eco-friendly environment like eco-friendly in nature other than carbon dioxide convergent process? Our main focus is on carbon dioxide. There are other focuses on nitrogen fixation for example and some others efforts that show that you can actually use electrochemistry to make chemicals. So, electrochemistry and electro-organic synthesis how it's called is becoming really a powerful tool to become more eco-friendly in the sense that the whole chemical industry uses a lot of thermal reactions to perform chemical synthesis and electrochemistry has the potential to lower the energy requirements to perform these reactions. Does this respond to your question? Okay. Thank you very much. So, then there is a question by Andrea Gucci. Can you speak to yourself? Hello, we can hear you, yes. I'm Andrea from DTU Energy at Denmark Technical University and basically when you present the effect of the modifier of this you modify the surface on water and CO2. I thought that in principle we could have some like a connection to the cationic effect that is actually presented by Karen Chan and at the beginning of the workshops. I was wondering if you thought about it. I'm going to say that I was not present at her talk and I'm assuming she talked about the role of the electrolyte in determining selectivity and the role of the cation in the electrolyte, is that correct? Yes, actually. Okay, perfect. Yes, I know her work. We have now changed the electrolyte in this case but it's something that we can add as an additional effect. What we tried to change was the heteroatom and specifically we looked at nitrogen and phosphorus but we didn't observe similar effects with phosphorus yet. I think there is more that can be done. We just didn't do it yet but it is a very nice suggestion. Thank you. Thank you very much. Okay, so thank you. Then there is Ogeny Sunday who has a question. Hello, can you say something please? I think there's a problem with your microphone because we cannot hear you. So, perhaps I'm reading your question or also you Francesca can read the question. It is at the beginning of your talk you showed a device that achieved 11.3% evolution of H2. How long did it take to achieve this and under what light conditions? Secondly, have you been able to address the degradation problem with the bis mode? For the hydrogen device we are under the one sun simulated light and we were in acidic conditions. So, instead of addressing the degradation problem with bis mode vanadate I didn't show today we did some direct interface discovery with the hydropower group and we do have some material some combination of bis mode vanadate catalyst that can help mitigate corrosion. We haven't yet solved the issue. I know that our groups in literature have tried their best to address corrosion and there are a few items out there. For example, the Czech group added vanadium oxide to the solution to shift the equilibrium in the other direction and they showed that with a sacrificial reagent in solution you can prolong the stability and there are also other groups that show that if you integrate a catalyst that can extract holes more efficiently then you can mitigate stability because at the very end, this is what I'm showing from my degradation analysis is that there are kinetics parameters that are affecting the degradation mechanism so if you can overcome those kinetics parameters then you can extract charges more efficiently and drive those charges for water oxidation. This answers Ogini's questions well and we have one last question which is by Dui Tai Nguyen Can you unmute? Yes? Hello? Hello, can you hear me? Yes, we can hear you, yes. Hello, I'm Dui Tai Nguyen I'm from Vietnam from the University of China and I'm from Hanoi. I have a question about multi-dome dot BIVO4 that it clears up the multi-dome dot path to improve the significance of the current so do you determine the location of multi-dome in the crystal? It is inside the crystal or on the surface of BIVO4 and in the crystal it occupies the position of the the most of the Vanadium or something So what we did we looked at this from the theoretical perspective and it occupies Vanadium sites and basically we look then at the relationship between molybdenum and oxygen sites. Okay, does this answer your question? One question, more time, is it in Hanoi now? It is now, it is nearly Wow, so thank you very much for staying with us until midnight. So with this I would like to thank Francesca and all the speakers we have had today so thank you all very much again Before closing the day let me just say that tomorrow we have kind of a special day of this conference because tomorrow we have a poster session which is always a particular challenge for an online conference, the poster session that will be tomorrow in the afternoon and tomorrow is also special because it's the only day where we have a talk in the morning but morning in Europe, so whatever your time zone is but so tomorrow we have in the morning Italian time Robert Schlögel who will give a talk and the day tomorrow will be chaired by Nicola Serian so from my side see you and thanks again to everyone and see you tomorrow