Electrocatalytic activity of IrO2-RuO2 supported on Sb-doped SnO2 nanoparticles

Electrocatalytic IrO2–RuO2 supported on Sb-doped SnO2 (ATO) nanoparticles is very active towards the oxygen evolution reaction. The IrO2–RuO2 material is XRD amorphous and exists as clusters on the surface of the ATO. Systematic changes to the surface chemical composition of the ATO as a function of the IrO2:RuO2 ratio suggests an interaction between the IrO2–RuO2 and ATO. Cyclic voltammetry indicates that the electrochemically active surface area of IrO2–RuO2 clusters is maximised when the composition is 75 mol% IrO2 - 25 mol% RuO2. Decreasing the loading of IrO2–RuO2 on ATO reduces the electrochemically active surface area, although there is evidence to support a decrease in the clusters size with decreased loading. Tafel slope analysis shows that if the clusters are too small, the kinetics of the oxygen evolution reaction are reduced. Overall, clusters of IrO2–RuO2 on ATO have similar or better performance for the oxygen evolution reaction than many previously reported materials, despite the low quantity of noble metals used in the electrocatalysts. This suggests that these oxides may be of economic advantage if used as PEM water electrolysis anodes