Electrochemical impedance spectroscopic (EIS) investigation of the oxygen evolution reaction mechanism of Ti/IrO2 + MnO2 electrodes in 0.5 m H2SO4 solution

Ti-supported IrO2(x) + MnO2(1 − x) coatings were prepared by thermal decomposition of a mixture of H2IrCl6 and Mn(NO3)2 dissolved in hydrosolvent. The nature and oxygen evolution reaction (OER) mechanism of the IrO2 + MnO2 electrodes in 0.5 M H2SO4 solution was studied by EIS measurements, emphasizing on the influence of coating composition, preparation temperature and the reaction potential. A mathematical simulation of experimental EIS data was carried out based on one state-variable theory. The simulated numerical number deduced the IrO2(x) + MnO2(1 − x) coating nature and oxygen evolution reaction mechanism during the process of O2 evolution. The inner relationships of coating nature with coating composition, and preparation temperature, the reaction potential, were analyzed and founded by these parameters of the Rs, Rf, Cf, Rct and Cdl. The Cdl and 1/Rct parameters have the high reliability in measuring the electrochemical activity of the IrO2(x) + MnO2(1 − x) oxide electrodes for OER, which can extend to that of other oxide electrodes.