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

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. © 2025 Wiley-VCH GmbH.