Active site reconstruction of a metal hydroxide/metal molybdate heterogeneous interface enhances electrochemical water oxidation

Abstract

Efficient, stable and economical water electrolysis catalysts are of paramount importance in energy transition and storage systems. Although numerous single compounds exhibit electrocatalytic properties, there are inherent limitations to achieving optimal performance. In this study, a highly active electrode was synthesized by constructing a heterojunction between Fe₂(MoO₄)₃ and Ni(OH)₂. The Ni(OH)₂/Fe₂(MoO₄)₃@TM heterojunction catalytic electrode demonstrated remarkable activity for water oxidation in a 1.0 M KOH electrolyte. It exhibited a low overpotential of 265 mV at a current output of 10 mA cm⁻², concomitantly maintaining excellent stability. Comprehensive characterizations, including electrochemical measurements, in situ ATR-FTIR, DEMS, TEM, in situ Raman and DFT calculations, collectively confirm the superior catalytic performance of the electrode. The results indicate that the synergistic effects of the fabricated heterojunction electrode optimize the d-band center, modulate the adsorption energies of *OH and *O at the electrode–electrolyte interface, promote electron transfer and surface reconstruction of the catalyst, and thus enhance OER activity and stability. The synergistic effect resulting from interface and reconstruction engineering can provide a new concept for the development of advanced electrocatalysts for sustainable energy applications.