(465e) Solvation Effects in Surface Electrochemistry for Oxygen Evolution Reaction Catalysis on Transition Metal Oxides

There is a clear need for a cost effective energy solution that can replace fossil fuels. In the past several years, electrolytic water splitting has been garnering significant attention as a potential solution to the production of hydrogen via sustainable but intermittent forms of energy such as wind or solar. This energy can be stored chemically as a bond in H₂ gas; the gas can then be used as a sustainable fuel or as a feedstock for commodity chemicals, such as the Haber-Bosch process, for which hydrogen is currently produced by steam reforming of methane.

The Oxygen Evolution Reaction (OER) takes place at the anode of electrolytic water splitting. Currently, there are no good catalysts for the OER, regardless of pH [1]. Many current ab-initio calculations for OER do not contain an explicit solvent [2], which has been shown to be significant for titanium dioxide [3,4], and for some other oxide surfaces [2]. It is necessary to understand how water impacts the stability of surface-bound OER intermediates to better design and understand electrocatalysts.

In this work we use DFT calculations and a minima hopping global optimization method to investigate how the inclusion of explicit solvent molecules affects the binding energies of OER intermediates at various intermediate coverages. Our results on IrO₂ indicate that hydrogen containing intermediates (*OH, *OOH) are significantly stabilized relative to O* by the explicit solvent. Relative stabilization of particular intermediates leads to changes in reaction energetics and ultimately in the calculation of theoretical overpotential, which is a measure of a catalystsâ?? activity [5]. Furthermore, solvent interaction with adsorbed intermediates has potential to be important for other electrochemical reactions, such as N₂ and CO₂ reduction. As such, an understanding of these solvent interactions could greatly impact how we think about catalyst design.

1. McCrory, C. C. L., Jung, S., Peters, J. C., & Jaramillo, T. F. (2013). Benchmarking heterogeneous electrocatalysts for the oxygen evolution reaction. Journal of the American Chemical Society, 135(45), 16977â??16987. http://doi.org/10.1021/ja407115p
2. Siahrostami, S., & Vojvodic, A. (2015). Influence of Adsorbed Water on the Oxygen Evolution Reaction on Oxides. The Journal of Physical Chemistry C, 119(2), 1032â??1037. http://doi.org/10.1021/jp508932x
3. Carrasco, J., Hodgson, A., & Michaelides, A. (2012). A molecular perspective of water at metal interfaces. Nature Materials, 11(8), 667â??674. http://doi.org/10.1038/nmat3354
4. Sun, C., Liu, L.-M., Selloni, A., Lu, G. Q. (Max), & Smith, S. C. (2010). Titania-water interactions: a review of theoretical studies. Journal of Materials Chemistry, 20(46), 10319. http://doi.org/10.1039/c0jm01491e
5.  Man, I. C., Su, H. Y., Calle-Vallejo, F., Hansen, H. A., Martínez, J. I., Inoglu, N. G., Rossmeisl, J. (2011). Universality in Oxygen Evolution Electrocatalysis on Oxide Surfaces. ChemCatChem, 3(7), 1159â??1165. http://doi.org/10.1002/cctc.201000397