Electrochemical hydrogen evolution on solid oxides RuO2, Ru0.7Rh0.3O2 and IrO2 from acidic water

Abstract

In contrast to traditional research with pure metals and intermetallic electrocatalysts for evolving hydrogen from acidic water, solid oxide catalytic electrode materials have been investigated recently. RuO2, Ru0.7Rh0.3O2 and IrO2 pellet electrodes have been prepared and the occurrence of the hydrogen evolution reaction on these oxides has been characterised by cyclic voltammetric and galvanostatic polarization curves in 2.5 M H2SO4 solution at room temperature. Measurements of thepH dependence of the surface charge densities on oxide particles have been carried out to correlate surface oxide properties with electrochemical properties. Reaction mechanistic pathways on metals and intermetallic compounds have incorporated the adsorption of hydrogen atoms on metal sites. It is suggested from the correlation of surface acid/base properties of oxides with their electrochemical properties that the sites of reaction are the surface oxygen atoms covalently bonded to suitable cations and possessing the appropriate energetics in the oxides.