Defect‐Driven Accelerated Reconstruction of Metal‐Organic Frameworks Toward High‐Performance Anion Exchange Membrane Water Electrolysis

Metal‐organic frameworks (MOFs) with tunable coordination environments provide model platforms for elucidating electrocatalytic structure‐activity relationships. However, the development of highly efficient MOF‐based oxygen evolution reaction (OER) catalysts has been hindered by the limited synthetic control over framework defects and their associated reconstruction pathways. Herein, we report a defect‐engineering strategy where a bicarboxylate ferrocene ligand (Fc) and a monocarboxylate linker (benzoic acid, BA) are co‐assembled on nickel foam to construct a defect‐rich NiFcBA‐MOF featuring abundant coordinatively unsaturated Ni sites. Compared to the defect‐free NiFc‐MOF, NiFcBA‐MOF exhibits markedly accelerated electrochemical activation, undergoing rapid in situ transformation into highly active oxyhydroxide species under OER conditions. As a result, NiFcBA‐MOF requires only 270 mV of overpotential to reach a current density of 100 mA cm −2 in 1 M KOH, outperforming the NiFc‐MOF (290 mV). When employed as the anode in an anion‐exchange membrane water electrolyzer, NiFcBA‐MOF delivers a current density of 1 A cm −2 at 1.85 V and maintains stable operation for 100 h at 100 mA cm −2 . This work demonstrates that rational defect engineering in MOFs can tailor reconstruction kinetics toward highly active oxyhydroxides, offering a viable route to MOF‐derived OER catalysts for technologically relevant electrolyzer systems.