Morphological Deterioration of Iridium Oxide-Tantalum Oxide Anode by Oxygen Evolution

Abstract

The morphology of an iridium oxide-based anode prepared by thermal decomposition and its variation during electrolysis at a high current density are investigated by SEM observation and elementary analysis using EDX, XRF, and XPS. The surface structure of the IrO2-Ta2O5 anodes is heterogeneous, consisting of cracks, IrO2 crystallites, and smooth areas with microcracks. Some parts of the coating layer gradually drop off with the increase in the number of cracks during the electrolysis, which results in the appearance of the new IrO2 crystallites from the inside phase of the coating layer. The relation between the morphological deterioration and the lifetime of the anode is also discussed.