(667g) Dynamics of Alcohol Oxidation Electrocatalysts Using X-Ray Absorption Spectroscopy

Electrochemical alcohol oxidation is an attractive alternative for the oxygen evolution reaction (OER) in water electrolyzers. Implementing selective, earth-abundant catalysts for alcohol oxidation could improve electrolyzer efficiency and economics. Nickel oxyhydroxide (NiOOH) is the accepted active phase of Ni catalysts for alcohol oxidation, but the material dynamics of the Ni during catalysis and reaction pathway are still unclear. In this work, we elucidate the mechanism of Ni mediated alcohol oxidation through in-situ x-ray absorption spectroscopy (XAS), using furfural and furfuryl alcohol as model compounds. In-situ tracking of Ni K Edge dependence on potential and reactant concentration reveals material reversibility and interplay between electrochemical Ni oxidation and Ni chemical reduction with alcohol. These changes and quantification of produced O₂ and alcohol oxidation products help explain limitations of Ni as an alcohol oxidation catalyst in OER-active potentials. Our findings are implemented in a microkinetic model to identify possible rate limiting steps and aid in understanding potential dependence of Ni K Edge positions. Insights from this rigorous model system are translatable to the broader goal of developing efficient, long-lasting catalysts for industrial deployment of electrochemical organic reactions powered by clean energy.