Sub-1 nm Ni3S2–FeMo6 nanosheets through cluster-nuclei coassembled strategy for high-efficiency water oxidation

Electrochemical water splitting for hydrogen production is currently constrained by the sluggish kinetics of the anodic oxygen evolution reaction (OER). NiFe-based catalysts have emerged as promising alternatives to precious metal OER catalysts due to their low cost and relatively high electrocatalytic activity. However, NiFe-based catalysts prepared by conventional synthesis methods suffer from a low density of exposed active sites and ambiguous structures. Herein, we report a straightforward solution-thermal strategy for constructing two-dimensional sub-1 nm nanosheets (SNSs) through the self-assembly of an iron-substituted polyoxometalate (FeMo 6 ) cluster with Ni 3 S 2 . The Ni 3 S 2 –FeMo 6 SNSs exhibit excellent electrocatalytic performance in 1 M KOH, achieving an overpotential of only 342 mV at a current density of 100 mA cm −2 and maintaining stability for 100 h at 10 mA cm −2 . The synergistic effect between Fe and Ni 3 S 2 effectively modulates the electronic structure of the catalyst, accelerating the formation of the active NiOOH phase. Furthermore, Fe incorporation actively enhances hydroxyl groups adsorption on the catalyst surface and facilitates lattice oxygen participation in the reaction. This work clarifies the role of Fe in NiFe-based electrocatalysts, providing new perspectives for developing facile-to-synthesize and high-performance electrocatalysts.