(6bc) Optimizing Electrocatalysts for Energy Storage and CO2 Conversion

My research aims to develop electrocatalysts for critical reactions in the energy sector. Analyzing global energy trends can identify catalytic reactions that are central to emerging problems, and mass and energy balances reveal the most promising paths to address these issues. Catalysts can be designed with a combination of density functional theory (DFT) calculations and model surface experimentation. And performance of industrially relevant catalyst morphologies can be evaluated with in-situ vibrational spectroscopy and synchrotron techniques.

Rapid increases in solar energy capacity and sustained use of fossil fuels require electrochemical energy storage and CO₂ conversion technologies. New water electrolysis installation needed to meet energy storage and CO₂-free hydrogen demands could incur up to a 50-percent increase in global iridium (Ir) consumption – an unsustainable spike in one of the world’s scarcest metals. During my Ph.D. studies under Prof. Jingguang Chen at Columbia University, I addressed this bottleneck by developing a core-shell Ir-metal nitride particle that reduces Ir loading by half and is near the center of the acidic oxygen evolution reaction (OER) volcano curve, according to DFT calculations. Importantly, the nitride cores are protected from the highly oxidizing environment by the IrO₂ shell, which was observed with in-situ X-ray absorption spectroscopy, and post-reaction electron microscopy. The Ir-metal nitride core-shell framework coupled with the effective DFT descriptor should enable optimization of Ir usage and surface binding energies in order to minimize Ir loading.

Global CO₂ avoidance targets are on the scale of hundreds of megatons per year, which may require fuels and chemicals across many sectors to be produced from recycled CO₂. There must, in turn, be a range of catalysts to convert CO₂ to CO, alkanes, olefins, and alcohols. Metal carbides were identified as robust and versatile electrocatalyst supports, capable of tuning activity for different reactions by matching carbide support with overlayer metal. High-surface area carbides, however, suffer from carbonaceous overlayers that limit synthesis and application. Metal nitrides have similar structure to carbides but are more easily synthesized with a “clean” surface. I am currently studying fundamental electrochemical energy storage and conversion reactions on nitride and metal modified nitride catalysts during a one-year DOE Office of Science Graduate Student Research Program in the lab of Dr. Radoslav Adzic at Brookhaven National Lab. I am using in-situ infrared spectroscopy to observe surface intermediates for electrochemical alcohol oxidation and CO₂ reduction on metal-modified nitrides. The technique helps reveal reaction pathways and can be correlated with DFT calculations to identify critical intermediates to accelerate catalyst development. I am also using in-situ X-ray diffraction and X-ray absorption spectroscopy to observe nitride stability under reaction conditions. This will provide valuable insight for future studies on selecting viable electrocatalyst candidates among this intriguing class of materials.

Moving forward, the methodology of evaluating global trends, performing mass and energy balances, and developing catalysts with DFT calculations, model surface studies, and in-situ techniques can be applied to address a wide range of issues in the energy field. As one example, the growing importance of CO₂-free hydrogen may benefit from substantial cost reduction of membrane-less electrolyzers. This technology presents a new slate of catalyst optimization issues from morphology to ion transport and cell design. These challenges can be met with an approach using fundamental electrochemistry and in-situ techniques, like the cases described above.

Teaching Interests:

I have strong interest in teaching across the breadth of chemical engineering core areas of study and believe that student success is built upon a mastery of mass and energy balances. I believe that developing problem solving skills is vital to an engineer’s training, and my teaching philosophy is that instruction should actively guide and foster these skills in a classroom, as opposed to simply lecturing. I have experience in this instruction style from my time as teaching assistant in an undergraduate kinetics course that was operated as a flipped classroom. I am also interested in developing students’ written and oral communication skills, which are too often under-stressed in engineering curricula. One of my undergraduate professors once told me that technical brilliance means little without the ability to effectively communicate to broad audiences, and I would emphasize this in any course I teach. I have enjoyed two teaching assistant opportunities as a graduate student and have been an invited lecturer on topics of water electrolysis catalysts for an electrochemical materials course and X-ray photoelectron spectroscopy for a surface science course. For specialized courses, I am most interested in teaching surface reactions and kinetics, scientific writing and communication, and chemical engineering applications of electrochemistry.