Magnetic Anisotropy Enables Spin‐Polarized Oxygen Evolution on FeNi Electrocatalysts

Spin polarization has emerged an effective tactic for regulating oxygen evolution reaction (OER) kinetics, yet the intrinsic structure-magnetism-catalysis relationship remains elusive. Herein, we report a morphology-driven magnetic regulation strategy in which FeNi spheres are mechanically ground into flakes, and disclose the correlation of magnetic anisotropy with OER activity. Magnetic characterization and Mössbauer spectroscopy confirm the preferential in-plane magnetic-moment alignment and domain coarsening in flaky FeNi-30. Micromagnetic simulations further reveal that two-dimensional flakes minimize domain walls and magnetostatic energy, enabling spin-selective electron transport in the first electron-transfer step. Consequently, the flaky FeNi-30 delivers markedly enhanced OER activity with a low potential of 1.52 V vs. RHE under a small magnetic field. Angle- and field-dependent electrochemical measurements directly correlate magnetic anisotropy and surface magnetization with OER kinetics, evidencing intrinsic regulation of spin-polarized electron transfer by shape-induced anisotropy.