Highly active and durable iridium nickel oxide oxygen evolution reaction catalyst in proton exchange membrane water electrolyzer

Abstract

Proton exchange membrane water electrolyzer (PEMWE) is the most effective way to convert and store renewable energy into hydrogen. The oxygen evolution reaction (OER) which occurs at the anode requires a highly active catalyst due to its sluggish kinetics. However, because high anodic voltage and strong acidic conditions are formed at the anode, most materials are unstable. Iridium oxide is known as the only active and durable catalyst for PEMWE OER. When mixture of iridium and secondary metal used as a catalyst, the iridium usage can be minimized and high activity can be expected due to surface amorphization. In this study, iridium-nickel oxide was synthesized through a simple molten salt method. When calcined at high temperature, a new phase of iridium oxide rather than rutile iridium oxide was synthesized, and it was confirmed that the new phase of iridium oxide had a high OER activity. The new phase of iridium-nickel oxide showed superior activity and durability compared to commercial iridium oxide in PEMWE unit cells.