Spin-conserved oxygen-redox coupling enables durable anion exchange membrane water electrolysis.

Oxygen-redox pathways offer a potential route beyond the thermodynamic scaling limitations of conventional metal-redox mechanisms, providing an opportunity to develop oxygen evolution catalysts for efficient and durable anion exchange membrane water electrolysis. However, direct O-O coupling through oxygen-redox chemistry remains difficult because the formation of triplet O2 requires spin-compatible oxygen intermediates, whereas spin-mismatched coupling is energetically unfavorable. Here we show that electrochemical reconstruction of V-doped CoS2 produces a cobalt oxyhydroxide catalyst with abundant coordinatively unsaturated Co-O units. These local structures strengthen Co-O electronic interactions, generate oxygen-hole states and activate Co-centered unpaired spins, thereby enabling spin-conserved radical oxygen coupling. The resulting catalyst couples low-overpotential OER activity (185 mV at 10 mA cm-2) with efficient anion exchange membrane water electrolysis performance, delivering 6.35 A cm-2 at 2.0 V and sustained operation at 1 A cm-2 for 2000 h. This work establishes spin control in metal oxyhydroxides as a design principle for efficient and durable anion exchange membrane water electrolysis.