The electrochemical characteristics towards oxygen evolution reaction of thermally prepared Ti/IrO$_2$–SnO$_2$ electrodes were examined. Two electrodes prepared with two different IrO$_2$ compositions were analysed in Na$_2$SO$_4$ 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 foundthat the surface electrochemistry of Ti/IrO$_2$–SnO$_2$ 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 differentpotentials 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 largecontribution to the electrochemically active surface area of Ti/IrO$_2$–SnO$_2$ anodes. It was found that the stability and the electrocatalytic activity mainly depend on changes in the IrO$_2$ composition of the electrode and its morphology during oxygen evolution reaction.
Volume 43, 2020
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