H2 remains an important chemical precursor in processes such as the Haber-Bosch process to synthesize ammonia and hydrocracking for refining of hydrocarbons and also exists as an alternative fuel for transportation. Currently, 95% of H2 is produced by steam methane reforming, whose byproduct is pollutant CO. Electrolysis is a clean, efficient method run at room temperature to split water into H2 and O2. However, electrolysis is not cost-competitive with steam methane reforming, utilizing large amounts of platinum group materials. Computational chemistry can give atomic and electronic levels of understanding of a material by identifying highly active facets of a known material or predicting the catalytic potential of unknown materials. We will model catalysts used in the oxygen evolution reaction, the half-cell reaction requiring the most catalyst and occurring many orders of magnitude slower than the hydrogen evolution reaction. In particular, we focus on the effect of the ensemble: focusing on different facets of metal oxides, characterizing all possible configurations of key reaction intermediates, and incorporating explicit solvation to fully understand the nuances of optimizing a premier catalyst such as IrO2 and a catalyst in development such as NiO. We will compare the reaction profile of the ensemble of key reaction intermediates in vacuum versus with solvation. Figure 1. A schematic displaying the different adsorption sites of oxygen in vacuum (LEFT) and example configuration of 6 H2Os arranged around these adsorption sites (RIGHT, side view and top view).

Towards realistic, in-situ modeling of the electrolysis of water: Ensemble and solvation effects

2019 Spring National Meeting

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