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 Ni₃S₂/NiFeOOH catalyst formed via in-situ electrochemical reconstruction of Ni₃S₂/NiFe-LDH. Interfacial charge redistribution stabilizes high-valent Ni³⁺/Fe³⁺ 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.