Electronic Locking of Labile Cobalt Spinel by Highly Dispersed Iridium for Stable Acidic Water Oxidation

The widespread development of proton exchange membrane water electrolyzers (PEMWEs) is severely impeded by the scarcity of iridium-based anodic catalysts. While non-noble transition metal oxides (TMOs) (e.g., cobalt spinels) offer a cost-effective alternative, they suffer rapid structural collapse in harsh acidic environments due to lattice oxygen over-oxidation and subsequent cation leaching. Herein, we report an electronic locking strategy to immunize labile Co₃O₄ against acidic corrosion by incorporating highly dispersed trace iridium (2.1 at%) via a cation-exchange-mediated topological transformation of ZIF-67 into ultrathin nanosheets. Rather than merely acting as active sites, the Ir dopants function as electronic modulators that lock the cobalt host in a high-valence state. This reconfiguration strengthens the metal-oxygen covalency, thereby suppressing the thermodynamically favorable dissolution pathway during the acidic oxygen evolution reaction (OER). Consequently, the optimized catalyst delivers 10 mA cm^-2 at an ultralow overpotential of 240 mV. When integrated as the positive electrode in a practical PEMWE single cell, it achieves 2.0 A cm^-2 at 2.28 V and sustains robust operation for 100 h at 500 mA cm^-2 (80°C). This work demonstrates how atomic-level electronic engineering can effectively tame the intrinsic instability of non-noble metals, maximizing precious metal atom efficiency for sustainable hydrogen production.