(126a) Frontiers in Water Oxidation Electrocatalysis

Water oxidation electrocatalysis is critically important for the climate-friendly production of carbon-neutral fuels and value-added chemicals. Global scalability dictates that catalysts cannot contain any toxic or precious elements. Many key materials challenges and requirements remain: How do we get earth-abundant electrocatalysts to perform at least as well as precious materials and that with long-term stability under harsh water oxidation conditions? Most reported catalysts oxidize only pure water; brackish water or seawater oxidation would be highly desirable, but selectivity towards oxygen remains challenging at high activity. And electrolysis must occur in acidic water under high input current density conditions to minimize mass transport resistance losses. No highly active non-precious electrocatalyst exists to date that does not undergo corrosion in acid. In catalyst development, we must take advantage of efficiency-boosting potential leveling by proton-coupled electron transfer mechanisms in aqueous electrolytes. To be able to do so, we must understand electrocatalytic mechanisms and identify structures and oxidation states of transient species during turnover with atomistic detail; particularly important is the precise characterization of the active site. We address recent progress in the field and highlight rational catalyst design criteria for the key frontiers.