An IrRuOx catalyst supported by oxygen-vacant Ta oxide for the oxygen evolution reaction and proton exchange membrane water electrolysis

Abstract

The sustainable development of proton exchange membrane water electrolysis (PEMWE) requires a dramatic reduction in Ir while maintaining good catalytic activity and stability for the oxygen evolution reaction (OER). Herein, high-surface-area Ta₂O₅ with abundant oxygen vacancies is synthesized via a facile process, followed by anchoring IrRuO_x onto a Ta₂O₅ support (IrRuO_x/Ta₂O₅). IrRuO_x and Ta₂O₅ work synergistically to afford excellent catalytic performance for the acidic OER. At 0.3 mg_Ir cm⁻², IrRuO_x/Ta₂O₅ only needed an overpotential of 235 mV to deliver 10 mA cm⁻² in an acidic half cell and needed a cell potential of 1.91 V to deliver 2 A cm⁻² in a PEM water electrolyzer. The characterization results show that doping Ir into RuO_x significantly improves the stability and the electrochemically active surface area of RuO_x. In IrRuO_x/Ta₂O₅, IrRuO_x interacts with Ta₂O₅ through more electron-rich Ir, indicating strong synergy between the catalyst and the support. The use of a metal oxide support improves the catalyst dispersion, optimizes electronic structures, facilitates mass transport, and stabilizes active sites. This work demonstrates that compositing Ir with less expensive Ru and anchoring catalyst nanoparticles on platinum-group metal (PGM)-free metal oxide supports represents one of the most promising strategies to reduce Ir loading and achieve an activity–stability trade-off. Such a strategy can benefit future catalyst design for other energy storage and conventional processes.