Heterointerface-mediated magnetic proximity accelerates oxygen evolution

Electrochemical water splitting is constrained by the sluggish and spin-sensitive oxygen evolution reaction (OER). The utilization of external magnetic fields can effectively modulate spin selectivity and enhance OER performance. However, external magnetic fields often induce non-spin effects and increase device safety concerns. Herein, we develop an external magnetic field-free strategy based on the magnetic proximity effect (MPE) by integrating ferromagnetic Fe₇S₈ core with a catalytically active WS₂ shell via electrospinning and chemical vapor deposition. The obtained Fe₇S₈@WS₂ delivers an overpotential of 222 ± 13 mV at 50 mA cm^-2 in alkaline OER. Comprehensive experimental and theoretical studies demonstrate that the ferromagnetic Fe₇S₈ core serves as an internal magnetic source that enables interfacial exchange coupling across the Fe-S-W heterointerface, thereby inducing proximity spin polarization in the WS₂ lattice and forming a spin-favored environment for OER. MPE-driven spin regulation can significantly modulate the electronic structure of WS₂, lower the *OOH formation barrier, and thus facilitate the OER kinetics. This work provides an external field-free strategy for designing efficient ferromagnetic OER electrocatalysts.