Oxygen evolution reaction of Ti/IrO2–SnO2 electrode: a study by cyclic voltammetry, Tafel lines, EIS and SEM

The electrochemical characteristics towards oxygen evolution reaction of thermally prepared Ti/IrO2–SnO2 electrodes were examined. Two electrodes prepared with two different IrO2 compositions were analysed in Na2SO4 electrolyte. Cyclic voltammetry, steady state polarization curves, impedance spectroscopy and open circuit potential were performed to investigate the performance and stability of these electrocatalysts. It has found that the surface electrochemistry of Ti/IrO2–SnO2 anodes are governed by the Ir(III)/Ir(IV) couple. The impedance spectroscopy investigation permitted to propose an equivalent circuit to describe the modifications occurred in different potentials during oxygen evolution reaction. The same equivalent circuit was found to describe both electrodes. Moreover, the double layer capacitance and microstructure analysis reflected that the inner surface makes a large contribution to the electrochemically active surface area of Ti/IrO2–SnO2 anodes. It was found that the stability and the electrocatalytic activity mainly depend on changes in the IrO2 composition of the electrode and its morphology during oxygen evolution reaction.