Abstract
Ni(3)Fe alloy electrocatalysts show promising activity for water electrolysis but are limited by sluggish hydrogen/oxygen evolution reaction (HER/OER) kinetics, and inefficient gas-liquid mass transfer under high-current-densities. Here, a superhydrophilic/superaerophobic 3D carbonized wood-loaded Ni(3)Fe-MoO(2) (Ni(3)Fe/MoO(2)/CW) heterojunction is designed to address these challenges. X-ray absorption fine structure (XAFS) and theoretical calculations reveal that the introduction of MoO(2) shortens the Ni─Fe bond length, induces electron transfer from Ni(3)Fe to MoO(2), and regulates the d-band center of Ni/Fe. These optimized Ni─Fe bonds and electronic structure enhance H─OH bond dissociation and H* adsorption/desorption, thereby accelerating the HER Volmer-Heyrovsky step. Simultaneously, for the OER adsorption evolution mechanism on Ni(3)Fe (1.462 eV), the strengthened Ni─O─Mo bond on Ni(3)Fe-MoO(2) heterojunction reduces the energy barrier (1.092 eV) of the rate-determining step, significantly improving catalytic efficiency. Thus, Ni(3)Fe/MoO(2)/CW displays good activity (HER: η(-10/-750) = 45/342 mV; OER: η(300/1000) = 251/306 mV). Notably, the large specific area of Ni(3)Fe/MoO(2)/CW from its nanosheet-particle structure enhances the electrolyte/bubble exchange at the gas-liquid-solid three-phase interface, enabling stable operation at 1000 mA cm(-2) for 24 h in an anion exchange membrane electrolyzer. This work demonstrates a MoO(2)-driven strategy for electronic modulation and metal bond regulation to boost HER/OER kinetics, advancing Ni(3)Fe-based catalysts toward practical high-current-densities water electrolysis.