We present our measurements of the oxygen electro-adsorption and oxygen evolution reaction (OER) on well-defined IrO2 and RuO2 surfaces, and the comparisons to theoretical results. The slow OER kinetics contributes the largest source of overpotential (inefficiency) to water-splitting devices. An OER catalyst can reduce this overpotential by stabilizing the OER intermediates via surface electro-adsorption. While this concept has led to the several OER-catalyst discoveries, the experimental relationship between the intermediate stabilization via electro-adsorption and the electro-kinetics is still elusive. We present a measurement of this relationship on IrO2 and RuO2 epitaxially grown on TiO2(110) single crystals. The high quality of the oxide films grown using molecular-beam epitaxy affords the ability to extract the electro-adsorption energetics, enabling us to quantify the relationship between the electro-adsorption and the OER electrocatalysis. We use this analysis to examine the validity of commonly assumed hypotheses, for example, the scaling relation—the idea that the surface binding energy can be approximated by the first bond to the surface. Finally, we will discuss the comparisons to theoretical calculations, in particular, what these comparisons imply for our ability to design future OER catalysts.

Electro-adsorption and oxygen evolution on well-defined oxide surfaces: Progress in theory-experiment convergence

2019 Fall National Meeting

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