The physical–chemical properties and electrocatalytic performance of iridium oxide in oxygen evolution

Abstract

An IrO2 anode catalyst was prepared by using the Adams method for the application of a solid polymer electrolyte (SPE) water electrolyzer. The effect of calcination temperature on the physical–chemical properties and the electrochemical performance of IrO2 were examined to obtain a low loading and a high catalytic activity of oxygen evolution at the electrode. The physical–chemical properties were studied via thermogravimetry–differential scanning calorimetry (TG–DSC), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical activity was investigated by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronopotentiometry in 0.1molL−1 H2SO4 at room temperature. The optimum condition was found to be at the calcination temperature of 500°C, where the total polarization reached a minimum at high current densities (>200mAcm−2). The optimized catalyst was also applied to a membrane electrode assembly (MEA) and stationary current–potential relationships were investigated. With an optimized catalytic IrO2 loading of 1.5mgcm−2 and a 40% Pt/C loading of 0.5mgcm−2, the terminal applied potential difference was 1.72V at 2Acm−2 and 80°C in a SPE water electrolysis cell.