Lattice Oxygen–Mediated Water Oxidation on Reconstructed Ni ₃ S ₂ /NiFeOOH Heterointerfaces

Developing cost‐effective oxygen evolution reaction (OER) catalysts for industrial current densities remains challenging, hindered by adsorbate evolution mechanism (AEM) scaling limitations and reconstruction instability. Here, we report a heterointerface‐engineered Ni 3 S 2 /NiFeOOH catalyst formed via in‐situ electrochemical reconstruction of Ni 3 S 2 /NiFe‐LDH. Interfacial charge redistribution stabilizes high‐valent Ni 3+ /Fe 3+ species and generates coordinatively unsaturated lattice oxygen sites, thereby activating the lattice oxygen mechanism (LOM). Combined operando spectroscopy, pH‐dependent kinetics, and isotope labeling confirm LOM dominance. Further theoretical analyses reveal that the heterointerface downshifts the metal d ‐band center and upshifts the O 2p ‐band center, optimized intermediate adsorption free energy. Benefiting from the compatible multi‐mechanism, the reconstructed catalyst demonstrates outstanding OER performance, only requires overpotentials of 196/305 mV to drive current densities of 10/1000 mA cm −2 in alkaline media, with robust stability for over 500 h. This work clarifies how interfacial electronic modulation connects pre‐catalyst reconstruction to LOM activation, providing a scalable design strategy for high‐current‐density OER electrocatalysts.