The oxygen evolution reaction mechanism at IrxRu1−xO2 powders produced by hydrolysis synthesis

Abstract

A mechanistic study of the oxygen evolution reaction (OER) has been performed for IrxRu1−xO2, x = 1, 0.6, 0.3 and 0, prepared by the hydrolysis synthesis. The oxides were characterized by X-ray diffraction, cyclic voltammetry and steady state polarization measurements. The electrolyte pH was varied in order to study the reaction order with respect to protons. The polarization curves recorded could be well fitted to a model consisting of a series of concerted electron-proton transfer reactions (mononuclear mechanism) with either of the second, third, or fourth step being rate determining. The expected trends for this mechanism with respect to potential and pH were observed in the experimental data and are consistent with DFT results for the adsorption energies of the adsorbates [Rossmeisl et al., J. Electroanal. Chem.607 (2007) 83–89] if the third or fourth step is rate-determining for RuO2 and IrO2, respectively.