Oxygen evolution reaction (OER) catalysis limits the efficiency of H2 production through water electrolysis and photoelectrolysis – routes to large-scale energy storage. Despite &gt;50 years of research the factors governing the activity of OER catalysts are not well understood. The paradigm to describe activity trends and predict new catalysts is based on active-site intermediate binding energies. The experimental data that forms the basis for this paradigm and to which theory is compared, however, has been largely collected on poorly defined materials. This led us to question the validity of the established activity trends and their mechanistic interpretation. We developed a thin-film electrochemical microbalance approach to studying OER electrocatalysis that minimizes confounding effects due to mass and electron transport through typical thick films or powders of varying porosity (JACS 2012, 134, 17253). We measure electrical conductivity in situ and use surface-analytical tools to clarify how composition and structure evolves during OER. We discovered that oxides convert to oxyhydroxides and incorporate Fe impurities which create the active sites entirely responsible for OER in record-activity Ni-FeOOH catalysts (JACS 2014, 136, 6744). We find new activity trends across the first row transition metals (JPCL, 2015, 6, 3737), opposite of the established ones, and propose a new view of OER on mixed-metal oxyhydroxides (JACS 2015, 137, 3638).

Activity trends and design principles for multi-transition-metal (oxy)hydroxide oxygen evolution catalysts

251st National Meeting (2016)

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