Preparation and evaluation of RuO2-IrO2, IrO2-Pt and IrO2-Ta2O5 catalysts for the oxygen evolution reaction in an SPE electrolyzer

IrO2-RuO2, IrO2-Pt and IrO2-Ta2O5 electrocatalysts were synthesized and characterized for the oxygen evolution in a Solid Polymer Electrolyte (SPE) electrolyzer. These mixtures were characterized by XRD and SEM. The anode catalyst powders were sprayed onto Nafion 117 membrane (catalyst coated membrane, CCM), using Pt catalyst at the cathode. The CCM procedure was extended to different in-house prepared catalyst formulations to evaluate if such a method could be applied to electrolyzers containing durable titanium backings. The catalyst loading at the anode was about 6 mg cm-2, whereas 1 mg cm-2 Pt was used at the cathode. The electrochemical activity for water electrolysis was investigated in a single cell SPE electrolyzer at 80 °C. It was found that the terminal voltage obtained with Ir-Ta oxide was slightly lower than that obtained with IrO2-Pt and IrO2-RuO2 at low current density (lower than 0.15 A cm-2). At higher current density, the IrO2-Pt and IrO2-RuO2 catalysts performed better than Ir-Ta oxide.