An investigation of the effect of RuO2 on the deactivation and corrosion mechanism of a Ti/IrO2 + Ta2O5 coating in an OER application

• Uniform and localized corrosion diagnosis in MMO anodes using EIS method
• Obtaining a MMO coating with uniform dissolution mechanism
• Producing a stable solid solution in the coating with nanostructured morphology
• Improved performance and increased service life in the coating composed of 30 wt.% RuO2

This article describes the investigation into the effect of RuO2 on the deactivation and corrosion mechanism of Ti/IrO2 + Ta2O5 coating in a sodium sulphate solution. Mixed metal oxide coatings within the composition, included in IrO2 + RuO2 + Ta2O5 with different percentages of RuO2 (10, 30 and 50 wt.%) on the titanium substrate, were prepared by thermal decomposition of a chloride precursor mixture at 480 °C. Surface morphology and microstructure of the coatings, were investigated by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Grazing Incidence X-Ray Diffraction (GIXRD) analysis.The systematic study of the electrochemical properties and corrosion behavior of these coatings was performed by cyclic voltammetry (CV), Accelerated Life Time test (ALT) and Electrochemical Impedance Spectroscopy (EIS). The results showed that the uniform dissolution of the active surface layers was the main mechanism for deactivation of the electrodes, especially the anode with 30 wt.% RuO2. Also, adding RuO2 up to 30 wt.% to the binary coating, because of the increase in active surface area and formation of the solid solution structure between ruthenium and iridium oxides, helped to improve performance and increase the working life of the anode.