Local Structure Modulation of Ir Single Atoms on Ce-Modified Cobalt Oxide for Acidic Oxygen Evolution

Abating iridium loading while preserving catalyst performance for acidic oxygen evolution reactions (OER) is essential, given the scarcity and high cost of iridium. Iridium single-atom catalysts on metal oxides offer a promising approach; however, their durability is often compromised by metal dissolution arising from low coordination and disruption of metal-oxygen lattice bonds under OER conditions. This study presents an iridium single atom supported on Ce-modified Co₃O₄ (Ir-Co₃O₄/CeO₂) electrocatalyst, where Ce incorporation modulates the local structure of the cobalt spinel, stabilizes the Ir single atoms, and improves Ir-Co interfacial interactions and metal-oxygen covalency, resulting in optimal active sites that significantly enhance catalytic activity and stability. Mechanistic insights derived from time-of-flight secondary ion mass spectrometry and molecular probe tests demonstrate that the OER on Ir-Co₃O₄/CeO₂ adheres to the adsorbate evolution mechanism pathway. Consequently, the catalyst exhibited a low overpotential of 254 mV at 10 mA cm^-2 and notable stability for 300 h. In a proton exchange membrane water electrolysis test, the stability was maintained for 90 h at 500 mA cm^-2 with a low degradation rate. The fabricated catalyst demonstrates superior practical applicability, surpassing most previously reported Ir single-atom catalysts with higher loadings.