Hydrogen oxidation reaction on modified platinum model electrodes in alkaline media

The mechanism of hydrogen oxidation reaction (HOR) in alkaline media is still under debate. In this work, we have systemically examined the HOR performance on planar Pt electrodes modified with ten different kinds of metal hydroxides/oxides (metal = Mg, Cr, Mn, Fe, Co, Ni, Cu, Ru, La and Ce). The HOR exchange current density (i(0)) increases monotonically with higher electrode's oxophilicity, which is determined by the current densities of CO stripping at 0.4 V vs. RHE (i(CO)@0.4 V). However, the Ru modification exhibits a clear deviation from the monotonic relation and it demonstrates a superior catalytic activity towards HOR, relative to other metal modifications. This unexpected result is ascribed to the reduction in hydrogen binding energy (HBE) owing to the modification of metallic Ru rather than its corresponding hydroxide or oxide. The present study indicates that the electronic effect and the oxophilic effect co-exist in the HOR on Pt-based catalysts in alkaline media, but the former one is of more significance. (C) 2019 Elsevier Ltd. All rights reserved.