Depth profiles and electrochemical properties of IrO2 electrocatalysts stabilized with TiO2

Abstract

IrO₂/TiO₂ mixed-oxide electrocatalysts of different composition have been studied by Rutherford backscattering spectrometry (RBS) and cyclic voltammetry. Obtained results indicate that enrichment of titanium oxide in the outermost part of the coatings occurs. Comparison with data for the RuO₂/TiO₂ system suggests that the enrichment is partially controlled by the concentration of the noble-metal ion in the precursor salt mixture and by the nature of the anions present in it, while it is practically independent of the nature of the noble-metal ion itself. Plots of voltammetric charge against iridium concentration in the coatings exhibit maxima for a sample with 30 mol% IrO₂. An interpretation of the electrochemical behaviour on the basis of the shape of composition depth profiles has been attempted.