Solution combustion synthesis of highly dispersible and dispersed iridium oxide as an anode catalyst in PEM water electrolysis

Abstract

Iridium based materials are state-of-the-art anode catalysts for polymer electrolyte membrane (PEM) water electrolysis thanks to their unmatched stability and performance in the acidic environment of common PEMs like Nafion®. However, their cost restricts their use in large-scale operations. To improve their utilization, identifying a synthesis method of nano-structured iridium oxide with a high active surface area, possibly in a supported form, is of great importance. For this aim, we developed a one-step and cost-effective solution combustion synthesis (SCS) method to prepare nano-structured IrO₂ and IrO₂-based materials suitable for PEM electrolysis. Among various materials prepared, the iridium oxide incorporated and dispersed in amorphous alumina showed a high surface area (131 m² g⁻¹) and the current density of 1.78 A cm⁻² at 1.8 V which is comparable to the performance of the state-of-the-art commercial membrane electrode assembly (MEA) made of IrRuO_x (1.8 A cm⁻² at 1.8 V) under PEM water electrolysis. Importantly, the dispersion of the material in the catalyst ink used for the preparation of the MEA was significantly superior compared to that of commercial IrO₂ nanoparticles and the amount of the precious metal in the catalyst made by SCS could be reduced by 45 wt% compared to that in the commercial MEA.