Hierarchical Spin‐Polarized Nanosheet Array for Boosting Ampere‐Level Water Oxidation Under Magnetic Field

Abstract The spin‐polarization strategy by manipulating magnetic electrocatalysts can promote the spin‐sensitive oxygen evolution reaction (OER) while developing efficient spin‐polarized materials toward ampere‐level OER is still challenging. Herein, a hierarchical inter‐doped (Ru‐Ni)O_x nanosheet array in situ grown on nickel foam is designed, which exhibits a distinguished overpotential of 286 mV at 1 A cm⁻² under 0.4 T magnetic field and a steady lifespan of 200 h at the ampere current density (i.e., 1 A cm⁻²), outperforming most reported state‐of‐art spin‐selective OER catalysts in alkaline electrolytes Integrating intrinsic and interfacial spin‐polarization on the inter‐doped (Ru‐Ni)O_x nanosheet array can significantly boost the catalytic activity for ampere‐level OER under a magnetic field. Specifically, the spin‐aligned Ru sites optimize the rate‐determined O─O coupling step to reduce the thermodynamic barrier of OER. Meanwhile, the charge transfer kinetics is promoted due to the accelerating spin‐selective electron transfer via spin pinning at the ferromagnetic‐antiferromagnetic interface. The design of a hierarchical spin‐polarized structure that integrates intrinsic and interfacial spin‐polarization strategies provides an additional route to developing a spin‐polarized OER catalyst capable of serving ampere current densities.