Proceedings of September Meeting 2016 (NFM16)
Publication date: 14th June 2016
Poor oxygen evolution reaction (OER) catalysis limits the efficiency of H2 production from water electrolysis and photo-electrolysis—clean routes to large-scale energy storage. Despite nearly a century of research, the factors governing the activity of OER catalysts are not well understood. I will discuss our recent advances in understanding the OER in alkaline media for earth-abundant, first-row, transition-metal oxides and (oxy)hydroxides. We find that the most-relevant structures for study are thermodynamically stable (oxy)hydroxides and not crystalline oxides. We show how thin-film electrochemical microbalance techniques allow for accurate quantification of intrinsic activity and how in situ conductivity measurements illustrates how materials are limited by electronic transport. We highlight the dramatic effect that Fe cations—added either intentionally or unintentionally from ubiquitous electrolyte impurities—have on the activity of most OER catalysts. In the absence of Fe we find activity trends across the first-row transition metals that are opposite of the established ones. We propose a new view of OER on mixed-metal (oxy)hydroxides where Ni or Co host-structures support Fe active sites. By rationally combining cations we tune intrinsic activity and electrical conductivity. The work thus illustrates design principles for electrocatalysts that may speed advanced hydrogen production applications.