Electronic Modulation and Surface Reconstruction of NiS ₂ for Enhanced Alkaline Oxygen Evolution Reaction Activity and Durability

ABSTRACT Practical anion exchange membrane water electrolysis (AEMWE) requires non‐noble‐metal oxygen evolution reaction (OER) anodes that deliver high activity while maintaining structural integrity under alkaline operation. Here, Fe‐substituted Ni disulfide (Ni _1‐x Fe _x S ₂ , NFS‐x) is designed as a conductive Fe‐modulated sulfide framework and combined with alkaline pretreatment (AT) to pre‐form a NiFe (oxy)hydroxide‐rich surface before electrolysis. DFT calculations show that Fe substitution narrows the NiS ₂ band gap by ∼0.44 eV and lowers the free‐energy barrier for the rate‐determining ^* O → ^* OOH step by 0.59 eV, while spectroscopic analysis indicates an increased average Ni oxidation state. The optimized NFS‐15 achieves an overpotential of 286 mV at 10 mA cm ⁻² . AT produces a largely amorphous/poorly crystalline NiFe (oxy)hydroxide‐rich outer layer on the retained sulfide core, confining subsequent reconstruction, suppressing catalyst detachment, and enabling superhydrophilicity‐assisted bubble release. In an AEMWE single cell, the NFS‐15‐AT/NF anode reaches 1 A cm ⁻² at 1.65 V, outperforms commercial IrO ₂ under identical conditions, and maintains stable operation for >200 h. This work demonstrates that integrating Fe‐induced electronic modulation of the sulfide framework with surface‐confined pre‐reconstruction provides an effective route to durable sulfide‐derived anodes for practical AEMWE.