The formation of unsaturated IrO x in SrIrO 3 by cobalt-doping for acidic oxygen evolution reaction.

Electrocatalytic water splitting is a promising route for sustainable hydrogen production. However, the high overpotential of the anodic oxygen evolution reaction poses significant challenge. SrIrO 3 -based perovskite-type catalysts have shown great potential for acidic oxygen evolution reaction, but the origins of their high activity are still unclear. Herein, we develop a Co-doped SrIrO 3 system to enhance oxygen evolution reaction activity and elucidate the origin of catalytic activity. In situ experiments reveal Co activates surface lattice oxygen, rapidly exposing IrO x active sites, while bulk Co doping optimizes the adsorbate binding energy of IrO x . The Co-doped SrIrO 3 demonstrates high oxygen evolution reaction electrocatalytic activity, markedly surpassing the commercial IrO 2 catalysts in both conventional electrolyzer and proton exchange membrane water electrolyzer.