Water Oxidation Promoted by Proximity-Induced Magnetism under Dzyaloshinskii-Moriya Interaction

Spin polarization governs the kinetics of multielectron water oxidation, yet benchmark catalysts like IrO₂ lack intrinsic ferromagnetism at ambient temperature, precluding spin control. Here, we exploit the interfacial Dzyaloshinskii-Moriya interaction (DMI) in Co/IrO₂ bilayers to induce spin-polarized states in the surface IrO₂. This DMI-driven spin polarization boosts intrinsic oxygen evolution reaction activity by 1 order of magnitude, achieving a turnover frequency of 4.17 s^-1 at 300 mV overpotential. Ferromagnetic resonance spectroscopy quantifies strong interfacial spin polarization via a 100% increase in the Gilbert damping. Spin-polarized DFT shows that DMI stabilizes a ferromagnetic ground state in IrO₂ and reveals that spin ordering alters the adsorption configurations and lowers reaction barriers for *OH dehydrogenation and O-O coupling. Inserting a Cu spacer eliminates DMI, quenching both magnetism and catalytic enhancement. Our results establish interfacial DMI as a general strategy to activate hidden spin states in nonmagnetic oxides, offering a new route to surpass the activity limits in water-oxidation catalysis.