(607a) Combining Single-Crystal Oxides and First Principles Computations to Understand Electro and Photocatalysis on Oxides

Hydrogen production from water through electro- or photo-catalysis is an attractive path towards the decarbonation of our energy system. However, the typical catalysts used for the water splitting reactions have important limitations in stability, activity or earth-abundance. An atomistic understanding of the catalysts surface and its reactivity would enable a better design of new catalysts but has been challenging to achieve.

With the advances in single crystal growth especially of oxides, very high-quality surfaces can be obtained offering a model platform to understand catalysis. I will report on the efforts to understand the oxygen evolution reaction on oxides (OER) under the Center for Electrochemical Dynamics And Reactions on Surfaces (CEDARs), an Energy Frontier Research Center (EFRC) from the Department of Energy (DOE). The first part of my talk will focus on RuO2 and IrO2 rutile has they are among the most attractive OER catalysts. I will show how theory and experiment on molecular beam epitaxy (MBE)-grown crystals can be combined to understand the complex process of hydrogen and water adsorption on these rutile oxide surfaces. I will then move to the understanding of how alloying MBE-grown IrO2 with titanium can dramatically increase activity and how computational insight can help rationalize this surprising finding. Finally, I will describe our work on photocatalysis where single crystal semiconducting oxides (SrTiO3 and TiO2) are studied with ultra-fast spectroscopy to elucidate the surface structure and intermediates formed during light absorption. First principles computations are here used to understand the atomistic processes probed by the spectroscopy.