Ions‐Migration‐Mediated Structural Stabilization in NiFe (Oxy)Hydroxides for Durable Alkaline Water Electrolysis

Abstract Elevating iron‐involved sites in NiFe (oxy)hydroxides significantly accelerates oxygen evolution reaction (OER) kinetics but often sacrifices stability due to extensive metal sites ablation during industrial electrolysis. Here, an ions migration‐induced stabilization strategy is introduced to explore robust NiFe (oxy)hydroxides catalysts for OER. The present approach involving cathodic polarization of Fe‐rich NiFe‐layered double hydroxides (LDH) facilitates selective substitution of Ni with Fe cations and deep substitution of oxyanions with OH ^‐ , leading to decreased layer thickness, enriched Fe sites, and aggravated lattice distortion in reorganized NiFe‐LDH (R‐NiFe‐LDH). Correspondingly, R‐NiFe‐LDH fully transforms into γ‐(NiFe)OOH with retained nanosheet morphology, reduced distortions, and dramatically inhibited Fe dissolution during prolonged OER. It achieves exceptional durability at 500 mA cm ⁻² , retaining ≈90% Fe over 5 days, substantially outperforming pristine NiFe‐LDH (50% Fe loss). Over 2 months, R‐NiFe‐LDH delivers only a 70 mV overpotential increase, whereas NiFe‐LDH decays by 140 mV in just 75 h. An anion exchange membrane water electrolyzer applying R‐NiFe‐LDH as both electrodes exhibit zero decay at 1000 mA cm ⁻² for 100 h, compared to a decay rate of 3.6 mV h ⁻¹ for the NiFe‐LDH counterpart. This work showcases a straightforward approach for engineering atomic arrangements in metal (oxy)hydroxides catalysts toward robust water electrolysis.