 All right, hi everyone. Thank you very much for being here today and also for welcoming me here in beautiful Lund. My name is Drew. I'm an assistant professor at McMaster University. I'm going to be talking about the in situ characterization of electrochemical processes of more specifically electrochemical electro catalyst materials using electron microscopy and using soft x-ray spectro microscopy. Now just for those of you who may not know, McMaster University is located up in Canada and so sometimes we look at it as the Sweden of North America for two reasons. One reason being that we're pretty far from North. The second reason being we're the best hockey nation in our respective continents and no offense to any Americans or any Finns that might be here, but you know being second not too bad, but ultimately we're a materials research intensive university. We also have strong medical school and a lot of other strong faculties, but Hamilton where we're located has traditionally been a steel sector town and so with that McMaster has developed a rich tradition in materials characterization research and because of that we have a lot of really fancy material characterization toys that we can play with in our research that have been really relevant to the kind of work that my team does. I'm not going to talk too much about this. I think probably most of us are on the same page that climate change is real. We're seeing unprecedented temperature increases and devastating impacts because of that and all comes back to the CO2 emissions that humans are emitting into the world. Reason being that at any given time we're consuming 18 terawatts plus of energy, 85 percent of that is coming from fossil fuel sources with associated CO2 emissions and climate change impacts. If we keep going like this things are not going to be good. I look at it as the important job of scientists and engineers to develop new processes and new technologies so that we can move towards sustainability. Now this is what I along with many of my colleagues envision as a sustainable energy future where we can use renewable and sustainable sources of electricity. Things like wind, things like solar, things like hydro. You could throw nuclear in there, not so much renewable but at least does not have carbon emissions. We want to figure out ways that we can use those to power all the things that society ends up on and if we want to talk about the production of fuels, chemicals and fertilizers one can we use renewable sources of energy to produce those and two can we use molecules that are readily abundant to us as precursors for producing those fuels, chemicals and fertilizers. So things like nitrogen to produce fertilizers, things like carbon dioxide to produce carbon-based chemicals and fuels, things like water to produce hydrogen. How can we achieve this and at the end of the day a lot of that comes down to electro catalysts. Today I'm going to be focusing mostly on electro catalysts for electrochemical CO2 conversion or electrochemical CO2 reduction whereby we convert carbon dioxide into fuels and chemicals, carbon-based fuels and chemicals using electricity. With that said we do work on several different areas of research in our group. CO2 conversion is one of them. We also have some battery related research, supercapacitor technology development and then selective oxidation of biomass wastes and byproducts that are produced from the production of biodiesel and bioethanol and then a big part of what we also do is in situ catalyst characterization. So understanding what the structure and properties are of materials under reaction conditions and that's largely going to be what I'm focusing on today but if you're interested in these other topics, if you want to chat about these things, you can always reach out to me. I'm happy to discuss and partner up if you're interested in working on any projects together. So just taking a look at what a simplified electrochemical CO2 conversion device looks like. We've got anode and we've got a cathode. There's our two electrodes where the reaction happens. Generally on the anode will be oxidizing water to form oxygen and on the cathode will be reducing carbon dioxide into these fuels and chemicals. These two are separated by an electrolyte membrane. It could either be a membrane or a liquid base electrolyte that allows for charge carrier transport. And if we zoom in on these electrodes they're comprised of nanometer catalysts, nanometer scale catalyst materials with high surface areas and a bunch of properties that we desire for good performance of this device. Now in terms of talking about the catalyst just take a step back to probably a lot of you covered this in high school chemistry but a catalyst is essentially a material that can accelerate the rate of a chemical reaction without being consumed in the process. And when we talk about properties that make a catalyst good, the first is activity. You know how fast can the catalyst make this reaction happen? The second is selectivity. How selective is this catalyst to you know one or two of our most desirable products because we're making a ton of different products we're going to have a separations issue on our hand. Then we need these catalysts to be stable. We want them to last thousands and thousands of hours and at the end of the day money dictates everything. We want them to be low cost so the economics of these technologies make sense from a large scale deployment standpoint. Taking that one step further what I'm going to be talking about today is electro catalyst. So essentially a catalyst is used for an electrochemical reaction or one could look at it as a catalyst that facilitates the conversion of electrical energy into chemical energy. So converting electricity using that to drive the conversion of carbon dioxide molecules into fuels and chemicals where we can make things like ethanol, carbon monoxide, propanol, ethylene, etc. And you know when I look at the deployment of the cyber technology I think the first step the first place that this is going to be integrated is at point sources of CO2 emissions and you know in Canada we've got many of these I know across the world there's many of these so if you have point sources of CO2 emissions and a lot of renewable electricity it could make sense to have this technology deployed as a proof of concept. So here's just a few different facilities that do have very concentrated point source CO2 emissions but you can imagine this list gets pretty long if you want to be all inclusive. I just show here a couple of examples. In terms of the products that we can convert CO2 electrochemically into there's about 15 or 16 different products that can be produced via CO2 reduction and a few of you know many of these are very widely used species in the chemical sector and the energy sector. So things that we really want to be able to produce but we don't want to have to rely on fossil fuels for some of these can be produced renewably from renewable sources such as ethanol but oftentimes that's produced by corn so you end up with a food versus fuel debate. If we can produce them electrochemically from CO2 we mitigate that food versus fuel debate as well so this can represent a nice way a sustainable way to produce these species that society depends upon without having to rely on food sources or without having to rely on fossil fuels. So all sounds great you know this is really nice we're going to save the world excellent what's the hold up why are we not doing this and at the very basic level there's two main things that are limiting the techno economic viability of this technology. The first is the cost of electricity ideally renewable electricity if we want to be able to produce these without a significant carbon footprint. Fortunately enough there've been significant cost reductions in renewable electricity to the point we're at two three four cents per kilowatt hour that's US dollars for renewable energy installations in certain regions of the world. Hopefully that can that trend continues and we keep moving down this y-axis sorry this x-axis to the point where this technology becomes more reality from an electricity cost standpoint. But then the y-axis the other thing that's really limiting us is the energy conversion efficiency of this process how efficiently we can convert electricity into the carbon-based fuels and chemicals that society depends upon. And it's researchers like myself and many of my colleagues around the world that really want to drive this energy conversion efficiency up we want to climb this y-axis through targeted research and development efforts. And all of that ultimately comes down to the catalyst and how one integrates the catalyst into these electrochemical devices. And there are challenges pertaining to the catalyst materials. The first is we don't have that many catalysts that can actually convert CO2 actively in selectivity into hydrocarbon and alcohol species some of these valuable species that society depends upon. In fact the only metallic catalyst that can do this is copper. So right there we look at the periodic table we're pretty limited in terms of the number of catalysts that we have available. The second is catalytic activity and so I show here this this line here indicates electro potential or electrochemical potential. As you go further down that means you need to provide more energy to drive this reaction. The reversible potential I show here for converting carbon dioxide into ethylene is at about 0.08 volts versus the RHE that means that electro potentials below 0.08 volts versus the RHE. Thermodynamically it is possible to convert carbon dioxide into ethylene but in reality we don't see the onset of ethylene production from carbon dioxide until about 800 millivolts below that reversible potential. That means every time we drive this reaction we're losing about 800 millivolts of energy which really kills our energy conversion efficiency. Then the next issue I want to highlight is selectivity. So thermodynamically you know if you're at minus 0.8 volts versus the RHE every single one of these reactions that I show here is thermodynamically possible. Also I'm only showing a small snapshot of the number of reactions that can thermodynamically happen under these conditions there's about 15 or 16 of them so thermodynamically we can produce all of these but really we want to find a catalyst that produces only one or two of those as selectively as possible otherwise we end up with a separations issue on our hands. And then last but not least we need these catalysts to last a long time. Right now the longest these catalysts are lasting is on the order of a couple hundred hours we need them to last five, ten, fifteen thousand hours so we have a long way to go in terms of the stability of the catalyst. And if you want to zoom out a little bit there's some systems level challenges of these devices based on the catalysts I've been talking about. One is the CO2 conversion you know you want to convert every single molecule of CO2 you feed into this device into a fuel and a chemical. You don't want CO2 coming out the other end you don't want CO2 crossing over and coming out the end of getting that utilization up to as close to 100 percent as possible is what we want. I talked about the energy conversion efficiency I talked about the high activity or in other words current and selectivity the durability once again 10, 15,000 hours is where we want to be we're nowhere near that right now and then at the end of the day you know this this device is not going to operate in a black box it's going to be needed to be connected to systems there's going to be balance of plant there's going to be other things connected to this overall device and so we really need to look at it from a holistic standpoint from a systems integration standpoint. So this is the framework this is a framework by which many groups myself included operate in terms of developing new materials for these technologies and integrating them into the technologies. So the first thing we go we go to the lab we mix some beakers together we stir some things around we heat them up and we synthesize these nano materials that we're targeting for having high activity stability selectivity for this reaction. We then characterize them to understand what the structure of properties are and then we test them out for their activity selectivity and stability towards our application of interest. From a fundamental standpoint what we want to do is we want to correlate the results of our materials characterization with the activity selectivity and stability that we measure electrochemically in our lab and what that allows us to do is that allows us to define what we call performance descriptors or essentially performance descriptors are the properties of a catalyst that make it good once we know what properties of a catalyst make it good we can feed that back into the design loop to hopefully develop catalysts that continue to prove upon themselves in an iterative way where ultimately we want to arrive at something that performs better than anything we've seen before and integrate them into an actual device. Now the important thing that we're doing is we're correlating the results of this materials characterization and activity testing oftentimes we want to use computational measurements or computational calculations to understand these materials using DFT or or transport models or monetary Carlo simulations doesn't really matter but the main thing is that when we're linking experiment and we're linking theory we really want the inputs that we provide to theory to be accurate and if we want our experimental insight to be accurate we want to know what the structure and properties are of our materials but ultimately we want to know what the structure and properties are of our materials under actual reaction conditions because those are the structures and properties that are performing the reaction it's not good enough to do the characterization of the materials after synthesis or after testing we need to know what those materials look like while they're actually performing the reaction of interest and so to that end I just have this little analogy to highlight the importance of in situ characterization you know put yourselves in the shoes of a detective if you go to a crime scene you want to figure out what happened okay you maybe you know what the crime scene looked like before the crime happened maybe you know what it looked like after the crime happened but if you only have those two data points at best you can speculate or you can guess at what happened during the crime this is this is very analogous to characterizing material once you synthesize it or after testing at best you can figure out you can take a guess at what the catalyst properties and structures look like under reaction conditions but really what we want to do is we want to be able to to shine a video camera we want to know exactly what happened during that crime or exactly what the structures and properties of these materials look like under reaction conditions and so it's crucial that we develop the techniques and we implement those techniques to understand electric catalysts under CO2 conversion conditions or under any reaction conditions using in situ approaches then just a quick a few definitions to highlight what I'm going to be talking about that the first is what we call in situ characterization which is essentially just studying a material under relevant reaction conditions you're simulating the conditions that that catalyst or that material would encounter in a real world device and then taking that one step further is operando characterization so when you study material under its realistic operating condition while simultaneously measuring the activity or selectivity of that material today I'm going to be largely using in situ characterization it's a little bit more of a catchall term some of what I'm going to be showing it could be considered operando characterization but at the very least in situ characterizing it as I mentioned is a catchall technique and it's a little bit more accurate for the techniques that we're developing and implementing and ultimately we want to be able to figure out what's happening in these catalysts in these electrodes across various length scales so I'm going to be talking today mostly about catalyst particles at the nanometer scale but these electrodes they're they're micron scale devices and involve the transport of reactants of products of electrons there's catalyst particles moving around there's polymer species in there there's conductive catalyst supports we want to be able to characterize these materials across these varying length and time scales to truly paint a holistic understanding of what's going on in these materials under reaction conditions and I'm going to be talking today about some techniques to look at the actual catalyst materials under reaction conditions and understand how they how they perform but before I dive in I just want to give a little bit of a confession because I know that many of you are probably brilliant physicists that I won't be able to keep up with or brilliant chemist material scientists so I just want to highlight I'm not a spectroscopist I'm not a microscopist I'm not a spectro microscopist I would call myself an electrochemist or an electrochemical engineer but I am going to be talking about spectroscopy microscopy and spectrum microscopy so I'm a little bit of an imposter but I do recognize the value and the importance of these techniques and I I gladly and I love collaborating with researchers that have complementary expertise so Professor Leila Soleimani and Nabil Basim at McMaster University they're very good at electron microscopy and then Adam Hitchcock and many of his colleagues around the world some of whom I know are here right now who are excellent spectromicroscopists and spectroscopists that I've been had the pleasure of learning a lot from and had the pleasure of working with to really do some some neat things and shine a light on the electro catalytic processes that we're working on. There's a variety of different techniques we can use to characterize material there's optical they're scanning electron x-ray today I'm largely going to be focusing on electrons and on x-ray characterization of materials. I won't be highlighting this too much but we do have a lot of in situ x-ray absorption spectroscopy efforts ongoing at McMaster University this includes for electro catalyst materials in what we call a membrane electrode assembly or just in a three electrode cell and using either fluorescence or transmission mode and using either synchrotron based x-ray absorption spectroscopy that we're doing a lot of at the Canadian light source or a relatively new recent innovation in the XAS community and that's a laboratory scale x-ray absorption spectroscopy where the national lab at the National Research Council of Canada has just set up a laboratory about 45 minutes away from McMaster and purchased one of these instruments that we've been getting access to to see if we can do laboratory scale x-ray absorption spectroscopy that has conventionally been limited to just synchrotron experiments and then also highlight we have one small effort on looking at thermal catalyst so catalyst operating at high temperature where we've developed a cell for doing XAS measurements on those as well but in terms of what I'm going to be talking about today I'm going to be focusing mostly on transmission electron microscopy and on scanning transmission microscopy x-ray microscopy and typography so two of the big techniques that we've been using to understand catalyst materials and how they operate so starting with TEM I'll just highlight we're super we're super spoiled we're super fortunate that at McMaster we have the Canadian Centre for Electron Microscopy so some of the most advanced electron microscopes in the world sample preparation capabilities we even have x-ray computed tomography capabilities and so the instruments are there and we also have the experts we have incredible researchers and technicians at the Canadian Centre for Electron Microscopy that really make this science happen that we've been leveraging a lot in many of the research efforts going on in my group and that I'm going to be talking about today if you're interested in using these facilities it's open it's accessible for everyone feel free to reach out to myself I'm the Associate Scientific Director of this facility or you can reach out to the facility directly at that email that I that I show there they'd be happy to work with you happy to help you out do the science and the research that you're really passionate about so just quickly I'll highlight the folks that have largely contributed to the work I'm going to talk about in terms of in situ TEM Ahmed was my first ever PhD student he just defended his PhD a couple weeks ago he's now a postdoctoral fellow he's really been leading these efforts and then collude Salab just joined our group last year and she's been picking up these efforts and working closely with Ahmed on these efforts that I'm going to be talking about a little bit so for those of you that don't know transmission electron microscopy or short form TEM you essentially take some electron beam you shine it through some optics you focus it on your sample and you illuminate your sample with those electrons that transmit through they transmit through onto a projection screen at the end of the day you can get an image that looks something like what I show here this nanometer scale imaging of a catalyst particle so here we've got a carbon supported platinum catalyst that so this is a typical TEM image that one could capture but many modern day TEMs are also equipped with analytical capabilities particularly energy dispersive x-ray analysis to look at where chemical where atoms are distributed through our samples and then select area electron diffraction to look at crystal phases and crystal structures that could exist under these materials in the last decade or so there's been a lot of innovation in terms of doing TEM on materials under electrochemical operating conditions and so to do that you essentially need a liquid electrolyte in there and you need electrodes and so to accomplish that some companies have developed these microchip electrochemical cells that they can encompass this electrolyte you flown electrolyte in they've got the silicon nitride thin silicon nitride windows that the electron beam can transmit through and then they've got our electrodes that can be that can be controlled by a potential set where we drop cast or we can deposit our catalyst particles for imaging under electrochemical reaction conditions this is the setup that we're using in our lab it's a commercial prototype system in the tip of this sample holder that's where a little microchip electrochemical reactor goes we've got the connections for electrolyte flow we can do that with a parasol pump a syringe pump or more recently we're using a pressure pump and then everything connects to this potential set that allows us to control a little electrode potentials and currents so the first catalyst we were interested in studying was palladium based catalysts and this is for a couple reasons first off um palladium is known to undergo phase transformations converting from palladium to palladium hydride under CO2 reduction conditions so we knew that we could use electron diffraction to take a look at phase transformations but then from a practical standpoint palladium is actually one of the most active catalysts for CO2 conversion it's active particularly towards formate at low over potentials you know over potentials about 50 millivolts to 100 millivolts um but one thing that's really interesting about palladium is it shows a very drastic change in selectivity from formate at low over potentials to carbon monoxide and hydrogen at high over potentials that are not really that well understood so this is essentially what our institute em holder looks like we've got the little microchip a reactor where we've got a glassy carbon working electrode where we can put our catalyst we've got a platinum counter electrode that wraps around the the electro chemical reactor and then a reference electrode that allows us to measure our working electrode potentials you can see this dark region here this is where our electrolyte flows into and out of the microchip we put all of that into the electron microscopy the electron microscope and that allows us to characterize our materials under reaction conditions but we also wanted to be able to correlate the structures that we see and the properties that we see by institute em with the actual activity and selectivity of these catalysts so we also prepare these large format these six centimeter squared electrodes we put into an actual reactor we use in our lab for measuring activity and selectivity we feed co2 in we run our electrochemical reaction the gas can be at the top of the reactor we feed to a gc gas chromatograph so that we can measure the the products that we're forming in the gas phase and then after the reaction is done we take that liquid electrolyte out and we analyze it by NMR to figure out what liquid products we're forming things like ethanol things like propanol so we've got this microchip electrochemical reactor we've got this large-scale electrochemical reactor and we wanted to electro deposit palladium catalyst onto the surface of the working electrodes in each of them and so what we did is we electro deposited palladium we did some some optical microscopy as well as scanning electron microscopy to look at the morphology of the catalyst and we found that between the two they had a very similar morphology and then ultimately what we wanted to do is make sure that they have a similar local reactive environment as well and we do a technique called cyclic voltammetry where we cycle the electrode potential between approximately zero and 1.5 volts versus the RG and we look at the responses the big peaks and plateaus that we see by cyclic voltammetry those are reflective of the chemistry of our catalyst particles as well as the chemistry of the local reactive environment and what we found is that the features between this large-format electrode and this microchip electrode were very similar which tells us we've got similar materials and we've got a similar reactive environment and so hopefully what we can do is when we measure the structure properties of the calcify institute TM we can correlate those to the activity and selectivity we see on this at large-scale electrode so we prepare these catalysts we prepare these electrodes we assemble the reactor we measure the activity and selectivity and like I mentioned we saw a format at relatively lower potentials or more positive working electrode potentials and that transition to carbon monoxide and hydrogen at higher over potentials and we really want to understand why that switch was happening we also performed electron diffraction to figure out what phase structures were present in the materials we first did this at open circuit potential so before we applied any electrode potential to our materials and we just illuminated the materials with an electron beam for a long time to make sure that our electron dose was not driving any kind of structural reconfigurations or phase transformations and holding it you know one five seven ten minutes even longer we didn't see any changes happening in these materials as a function of erading in it with electrons and so what that told us is that hopefully any changes that we see during these measurements are due to the application of electrode potential and not due to the beam doses that were that were providing so we started to run these measurements applied electrochemical CO2 conversion conditions we saw particles growing particles moving around a lot of things happening that I'll summarize a little bit at the end here but what I show here is I show an image of the electrode as prepared so you know we deposited our electrodes and then we recorded a bunch of videos during the CO2 conversion CO2 conversion process and you know we probably don't want to sit here all day and watch videos but this kind of summarizes the starting point and the end point and we were able to capture data all the way along during this structural retransformation that we we observed then in terms of looking at the phase structures present in these materials this is the electrode potential profile that we used where what we would do is we would what we called recondition our catalyst by applying a potential electrode potential of 1.2 volts versus the RHE and what that did is that got our catalyst back into metallic palladium form and then we progressively stepped our catalyst to more cathodic electrode potentials to look at how that metallic palladium would convert into palladium hydride to really understand that phase structure transformation that occurred and so here is two videos that kind of show what happens when we switch from 1.2 volts versus the RHE to minus 0.2 volts versus the RHE which is under electrochemical CO2 reduction conditions here you see the particles kind of growing and here you can see the diffraction rates shrinking and growing shrinking and growing when the diffraction range shrink that means the lattice is expanding that's because we're forming a palladium hydride these protons are intercalating to the structure and we're seeing that lattice expansion and when we go back to 1.2 volts versus the RHE the protons are leaving that structure so that palladium hydride is converting back into metallic palladium so here's all the diffraction the diffraction patterns that we collected at the various electro potentials and what that allowed us to figure out is that at higher electro potentials palladium is in its metallic form then it slowly converts into an alpha palladium hydride and then a blade of palladium hydride at more reducing potentials and as we go further and further more negative in electro potential we're putting more and more hydrogen into that palladium hydride structure causing that lattice to continually expand so this cartoon kind of paints a picture of what we learned from our institute TM measurements where we know that once we apply CO2 conversion conditions we're forming these palladium hydride particles so protons are intercalating into the palladium but then we observed a few different degradation phenomena the first was agglomeration we saw that occur due to Oswald ripening where particles would kind of migrate together and form larger particles to minimize their surface energies but we also some saw some particles detaching from the electrode surface flowing across the electrode and attaching again to other particles forming these big these big agglomerate structures we also saw particle detachments of particles just falling off the electrode and flowing away we think that was largely due to the mechanical instability from the volume expansion and contraction so our palladium is growing and shrinking growing and shrinking as it interconverts between metallic palladium and palladium hydride we're also forming some bubbles at the electrode surface and the electrode is also flowing so we think that this detachment was largely due to those mechanical forces at play and then we also saw the formation of these kind of spongy porous like structures that we believe is due to adsorbate induced restructuring where the palladium surface get strongly absorbs carbon monoxide species that have kind of an annealing effect on the structures and cause the formation of these porous structures we have some electrochemical data I didn't show it here but we have some electrochemical data that shows that that is likely what's happening but it was really interesting to see those structural reconfigurations then I might jump a little bit ahead here but long story short we we collaborated with some friends at the Danish technical university to understand what impact this palladium hydride structure was on was having on the selectivity change between formate and carbon monoxide and what we found is that the the formate production pathway actually went through where a carbon dioxide molecule would go close to the palladium hydride surface and there would be a surface hydrogenation there would be hydrogenation of that carbon atom moving towards the production of formate and what was really interesting is we figured okay if it's a hydrogenation of the carbon atom by a surface or a near surface hydrogen atom we probably want as much hydrogen as possible inside that palladium hydride but that's a little bit counterintuitive to the electrochemical data because we know that as we go more negative in electro potential we're putting more and more hydrogen into that palladium hydride structure so you would think that we're producing more and more formate at lower potentials but in fact we're seeing the the exact opposite we're seeing less formate at more reducing conditions and we're seeing more carbon monoxide and so that's where dft was really helpful for understanding the energetics of this reaction and what we found is that yes while we do want hydrogen at the surface or near surface of palladium hydrate particles as we go to more reducing potentials the the pathway for converting CO2 into formate only gets marginally more thermodynamically favorable whereas with the carbon dioxide to carbon monoxide reaction pathway it got much much more favorable as we go to more reducing potentials and so taking the energetics of that were calculated by density functional theory our collaborators did some microkinetic modeling that showed essentially that even though we want that that hydrogen structures for producing the formate it's really the electrode potential the reaction thermodynamics that change that causes this this reaction to be more favorable for producing carbon monoxide at at reducing potentials so now i'm going to switch gears a little bit and talk about in some in-situ scanning transmission x-ray microscopy so that's a mouthful stixm it's generally what it's called stxm stixm stands for scanning transmission x-ray microscopy so you're going to hear that acronym you can see that acronym a lot that's what it that's what it stands for and then i'll talk a little bit about some typography efforts that we did at the end of this section but before i do so i really want to highlight the people that made this possible largely professor adam hitchcock just a just an incredible researcher incredible scientists world leading expert at the at the development and use of stixm techniques and then we have a co-advised student chang yang zhang who actually just offended his phd two weeks ago he's sticking around as a postdoc fellow for a little bit and then haytham iraqi a phd soon also in in adam's group at McMaster university and a lot of us collaborate very actively on on these research efforts for using these advanced techniques to understand our electrochemical and electrocatalytic processes so essentially what stixm is is it provides microscopic and spectroscopic characterization of materials so put your materials in run your sticks and measurement and it spits out a microscopic image that looks like this so similar what one might capture from uh tm transmission electron microscopy but the beautiful thing is that every single pixel in this image has a corresponding x-ray absorption spectra associated with it so you can find regions of your catalyst and draw a box and you can figure out what kind of chemical species are present with spatial resolution so that's really one of the powerful capabilities of this technique is you get microscopic data as well as chemical speciation with spatial resolution so a really beautiful technique for understanding what our materials look like and what chemical species are present and where those chemical species are present so ultimately what we can do is we can paint a picture that looks kind of like this where we've got copper and then we've got copper in various oxidation states and we can figure out exactly where those different copper species exist the the first thing we did is we just wanted to make sure that this technique worked for looking at electric cast particles so we used some metal nitrogen carbon catalyst developed in our in our lab these are very heterogeneous catalyst particles and people don't really know what structures are the active sites in these materials so we characterize them by stixm found out that these catalyst particles consisted of two distinct regions one was these kind of dark parts these these nanoparticles and the other was these what we call the carbon matrix or these kind of graphitic carbon regions that didn't seem to have much nickel present in them i'm skipping over a lot of information but what we did is we used stixm to identify that the the dark particles largely consisted of metallic nickel and nickel sulfide which are not necessarily very good for electrochemical CO2 reduction but it's these these carbon-based regions that had that had nickel 2 plus sites very similar to this nickel tpp molecule present in their structure that we were able to identify and correlate to the results of the electrochemical activity we were seeing in our lab so gave us a lot of insight into these very interesting materials and how they operate but that was all ex situ characterization that was just on materials as prepared chun yang and adam being excellent scientists they want to put on their detective hats bust out their magnifying glass that bust out their detective pipe and their video camera and figure out exactly what's happening to electro catalyst materials under reaction conditions they wanted to take this stixm technique and apply in situ capabilities to it and so they collaborated um or sorry this is actually going back a few years this is a first generation of the in situ stixm cell that was developed by adam's team at at McMaster University so this was the first generation and it was this essentially this electrochemical balance of plant connected with this microchip electrochemical cell that has a gold working electrode a gold reference electrode and gold counter electrode and you take your materials and you can put them on this working electrode and do sticks and measurements on them and they had some very nice efforts where they looked at the electro deposition and electro oxidation of copper particles and this was a really nice proof of concept that this technique could in fact be used to look at materials electrochemically active materials under reaction conditions so we've been collaborating very nicely with professor martin ops who who is actually here today so hi martin and his student pablo igneo at the university of bay ruth who really who developed this really beautiful next generation in situ stixm cell and so it's it's got microfluidics that allow the electrolyte to go in the electrolyte to go out and then it's a pcb board where we've got all the electrochemical all the electronic interconnects that connect to this microchip um electrochemical reactor so just a beautiful design developed at the university of bay ruth that has really largely been leveraged in all of the efforts that i'm going to be showing here so a big shout out to martin and and pablo who've done really nice work in this space this is what the stixm cell looks like in situ um so and this is the chamber the stixm chamber at the canadian light source that we've been using and in terms of the scientific question that we wanted to answer there's a lot of debate in the electrochemical sue to conversion community about for copper catalyst what oxidation state they're in under reaction conditions so personally i've always believed it's metallic copper we're at electrochemical reducing conditions it's got to be metallic copper during our electric catalysis but there is a significant portion the literature that thinks or states that copper oxide actually still exists under electrochemical sue to reduction conditions and enhances the electric catalysis for co2 conversion and so we look at stixm as a beautiful way of being able to probe this do copper oxide species exist under reaction conditions and if they do exist where do they exist in the catalyst or why might they exist and so chun yang said into the lab for electro depositing copper onto the working electrode of these stixm chips you did that just by doing some cyclic voltammetry and so here a shown image of just a blank gold electrode and then after the in situ copper deposition you can see copper particles kind of decorated all over the surface that we use as our electrode for in situ sticks and measurements here's some measurements that were done just down the road at the softy max beam line at max four where what chun yang showed chun yang and adam showed is that depending on the electro deposition process used we could get very different copper based electro deposit structures that were formed so this gave us some insight into what the best way to prepare these catalyst particles are that was amenable to to sticks and measurements then once they once they did the electro deposition of copper we also measured a bunch of reference spectra we had metallic copper copper one plus oxide copper two plus oxide as well as a few other reference spectra which we used to ultimately fit the spectroscopy that we're producing via our sticks and measurements using an svd matrix method the other thing that was a really really clever innovation is figured out that we could do sticks and measurements at just four select energies so one at 920 electron volts which is the pre-edge one at 933 3.5 electron volts which is a signature of both copper one plus and metallic copper 937 which is which is based on metallic copper and then 960 which is at the post edge region and so what we could do is we could accelerate these measurements by just strategically targeting four x-ray energies to do these measurements at that would allow us to figure out what chemical species were present in these materials so ultimately we put these materials into the institute sticks and chamber and we did these four energy sticks and stacks which allowed us to figure out what chemical species were present and where so you can see here the green regions are copper one plus oxide and the red regions are metallic copper but then we want to figure out how that changed as a function of electro potential so what we did is we applied increasingly more negative electrode potentials to figure out how these copper particles change oxidation state and how they change structure shown on the right is the measurement protocol we used whereas first we we condition our catalyst at 0.4 volts for CRG so we'd hold it there for 30 seconds or so just to make sure that the starting state of our catalyst material was was the same before every measurement and then we would apply a negative applied electrode potential first for a couple of minutes just allow the materials to stabilize then we do that four energy sticks and stack measurements so just sticks and measurements at four different photon energies that took about seven minutes then we did a full stack measurement so doing a sticks and measurement at the entire copper two across the entire copper two p x-ray photon energy region and that gave us a bunch of data that we could we could use to analyze the process is occurring under electrochemical conditions and the resulting morphologies and and chemical oxidation state states so here's a typical example of a result that was obtained this one was just at 0.4 four volts versus the RHE so here's an image the the microscopy image that comes out and what this allowed us to do is it allows to look at a particular region of the catalyst where we saw as we would expect at 0.4 volts for CRG we saw a mix of copper one plus oxide and metallic copper this is a result from the four energy sticks and stack measurement this is from the full stack measurement and we found that the results between the two were quite similar so we found this this four energy stack measurement was actually pretty good at accelerating the rate at which we could collect data that um that had useful information in it so then what we did is we we applied increasingly more cathodic electrode potentials and when we get down to minus 0.6 volts versus the RHE this is really where we're in the CO2 reduction electrode potential regime what we found is when as we step to more negative electrode potentials the copper oxide species would gradually reduce to be metallic copper the other thing that we saw is that from going and we can look at this image where my my pointers for example going from the four energy stack measurement to the full stack measurement we saw that more species were reduced during the full stack measurement than in the four energy stack measurement and this is not because of the measurement protocols we're using this is because some of that copper oxide reduction to metallic copper was kinetically limited we found it takes a few minutes to about 10 minutes for all of those catalyst particles that thermodynamic dynamically are going to be reduced to be reduced so it's not it's not an instantaneous copper oxide reduction to metallic copper um sometimes it takes a few minutes to get those kinetics to go but ultimately what we did see is that under electrochemical CO2 reduction electrode potentials so this minus 0.6 volts versus the RHE everything was in its metallic form this kind of just paints that picture where the um where these bar graphs labeled with the square is from that four energy stack measurement and the star is from the full stack measurement and you can see that you know as we go to more negative electrode potentials we've got metallic copper and as we go from the four stack measurement four energy stack measurement to the full stack measurement there is even a further reduction just because of the kinetics of this electrochemical reduction of metal of copper oxide into metallic copper and as I highlighted it's these negative electrode potentials minus 0.2 minus 0.4 minus 0.6 volts versus the RHE which is where electrochemical CO2 reduction can occur and we are basically pure metallic copper under these conditions telling us that metallic copper is the active site for our reduction then we want to ask ourselves why is the community seeing copper oxide under CO2 reduction conditions why are there literature reports that believe copper oxide plays a role in CO2 conversion studies or CO2 conversion processes where we really don't see any and thermodynamically we would be incredibly surprised if copper oxide did exist so what we did is we deposited a very thick electrode so we electro deposited a lot of copper onto these these microchip electrochemical reactors and we did stick some imaging and what we did is when we had these very thick copper electrode deposits we found that there were regions of these copper catalysts that were not electrochemically responsive no matter what electrode potential we went to their oxidation state did not change at all and the reason that is is because we think that these particles have become electronically disconnected from the electrode so there's these big agglomerates some of those copper oxide regions are insulating and so when we apply negative electrode potentials nothing happens they are not electronically connected to that working electrode anymore and what this told us is maybe this is what the community is seeing oftentimes in the devices used for different institute measurements you've got very thick catalyst layers very thick electrodes where likely some of that copper oxide probably just becomes electronically isolated from the rest of the electrode and continues to persist even under the reducing conditions and then we want to take this one step further and there's been a lot of recent developments in the area of sticks and typography and so at a at a simple level and that simple level is pretty much the only level I can understand it at sigmail tendency to collecting sticks and measurements in the way that I've shown in the last few slides you can also perform typography where electrons that are diffracted through your sample are collected by a ccd camera and that allows for additional data to be collected to hopefully overall improve the resolution of these measurements and so adam as he does always wants to push techniques forward make new advances chunyang also wants to do that and is very good at doing that and so what we are able to show is that sticks and of these nickel metal nitrogen carbon catalysts that I showed previously sticks and measurements gave us a resolution on the order of about 60 nanometers but when we apply typography you can see how much sharper this image is on the right versus the one on the left so just visually you can tell that the resolution is increasing and we found that we're able to take the sticks and resolution from about 60 nanometers down to about 20 nanometers by applying typography techniques during these sticks and measurements so of course we want to put our detective hats on we want to look at these materials in situ and so we decide once again to look at copper catalyst particles and so we deposited copper catalyst particles onto the working electrode we zoomed in on a single particle here by sticks and you can see it's a bit of a blurry mess of a copper particle but when we use when we use typography we can actually resolve that individual copper particle that had a somewhat cubic structure and we want to see how that single particle evolved in oxidation state and morphology as a function of applied electrode potential so what we did is we took that catalyst particle initially we measured at open circuit potential and then we started to apply progressively more negative electrode potentials and we found once again consistent with the sticks and measurements as we went to more negative potentials all of the copper oxide in those materials were reduced but in addition to the electrochemical reduction of the copper oxide we saw we also saw this catalyst particle start to evolve start to change from like a cubic structure initially to form these dendritic kind of broken structures as a function of applying electrochemical CO2 conversion conditions so very interesting that this technique allowed us to look at a single catalyst particle track oxidation state changes and track morphology changes all within one one very powerful measurement so now just moving forward we want to continue to develop and explore these techniques for in situ characterization of materials I talked today exclusively about electro-deposited catalysts we want to be able to now look at more real-world catalysts so catalysts generally an electrochemical device the electrodes are made by taking a catalyst ink so dispersing a catalyst particle in in a solvent adding a bunch of ionomers or binder and then coating it on to an electrode so we want to be able to take those kind of real-world catalysts those catalyst particles that are probably in some sort of catalyst ink deposit them onto our electrochemical microchip reactors so that we can characterize real-world particle catalysts so we have these shadow masks that we've been using to try and do that where we can drop cast or catalyst particles we've had some success putting our catalyst particles onto the working electrode we just need to optimize and refine that technique and then do actual in situ measurements on these materials the next thing we want to do is you know I showed kind of catalyst scale characterization of these materials we want to have multimodal or correlative techniques to look at the catalysts and electrodes and all the processes that can occur under reaction conditions and really gain a holistic understanding bridging what happens at the nanometer scale all the way up to the micron scale and that will give us a full understanding of these electrochemical processes occurring in these devices that will hopefully allow us to improve the performance of these materials and improve the performance of these devices the next thing we want to do and this would be super cool is all of these products that we're forming these carbon dioxide derived products are carbon based and the beautiful thing about Styxam is with some recent innovations and advancements it's possible to do sticks and measurements at the carbon edge and so we want to see if we can actually see spectroscopically the types of products that are being formed within that that electrochemical microchip reactor and then last but not least we'd really like to understand you know you can't just look at the catalyst when you're looking at electrochemical CO2 conversion condition the the electrolyte membrane matter the ionomer matters and those catalysts the electrolyte interfaces matter and they change as a function of electrochemical CO2 conversion conditions the beautiful thing about Styxam is it soft x-rays so you can look at the the types of structures the soft materials present in these electrolyte membranes and in these ionomers and so we want to be able to spectroscopically or spectrum microscopically microscopically characterize these catalysts and these electrolyte membranes as well as their interfaces and find how they change as a function of reaction conditions so with that said just another shout out to the people that did all the hard work that really made these research projects happen and have been driving these techniques forward and applying them to advancing our understanding of electrochemical processes a shout out to the whole team so this is us just hanging out in a park in this in this previous summer and then a shout out to the facilities that have made this research possible including the max four which is just down the road here as well as the funding agencies that have supported this research with that said thank you all so much for your your kind attention and and being here today i'm happy to answer any questions here's our website if you want to learn more my email address is here feel free to reach out if you want to chat if you have any questions if you're interested in the work that we're doing thank you very much and i'm happy to answer any questions and engage in any discussions that any of you would like to thank you