Hydrogen production by electrochemical water splitting is a technology with the potential to meet the growing worldwide demand for sustainable and clean energy. However, the development of cost-effective catalysts to replace noble metals, such as platinum or ruthenium, remains crucial for large-scale hydrogen production. This study presents the synthesis of a transition non-noble metal-based ternary NiMoCo hybrid nanowire array as an efficient bifunctional electrocatalyst for overall water splitting in 1.0 M KOH electrolyte. The catalyst exhibits a low cell voltage of 1.56 V to achieve a water-splitting current density of 10 mA cm⁻² together with long-term stability with only 5% of the initial current lost after 100 hours. X-ray absorption spectroscopy confirms that the addition of Co to the binary Ni–Mo system results in a highly mixed chemical binding state with modulated electronic structures. Density functional theory (DFT) calculations reveal that the Co atoms on the ternary alloy become catalytically active sites and facilitate adsorption of intermediates by ensuring preferable interactions between the reactants and the catalyst surface in comparison to the binary counterpart. This work provides a new direction along which to activate binary alloys to further enhance their catalytic abilities in overall water splitting.

Seawater electrolysis is a promising route for hydrogen production using inexhaustible seawater resource. However, chloride ion (Cl⁻)-induced corrosion and limited catalytic activity pose challenges to the development of non-noble metal catalysts for seawater electrolysis in anion exchange membrane (AEM) electrolyzers. Herein, we fabricated an NiMo/NiMoP heterointerface to construct a strong built-in electric field (BEF) and further elucidated the impact of BEF on both electrocatalytic enhancement and corrosion resistance during seawater electrolysis. Theoretical simulations revealed that BEF benefitted the H adsorption, and simultaneously, the presence of an NiMoP layer effectively impeded Cl⁻ adsorption owing to steric effects. The NiMo/NiMoP heterointerface with a continuous BEF (NiMo/NiMoP-C) exhibited superior activity and durability compared with its counterpart with isolated BEF (NiMo/NiMoP-I). The excellent performance of NiMo/NiMoP-C in AEM seawater electrolysis was confirmed as it exhibited a current density of 1.0 A cm⁻² at a cell voltage of 1.8 V and a durability for over 350 h. This study provides a novel strategy for BEF construction to achieve a highly active and corrosion-proof non-noble metal catalyst for hydrogen production through AEM seawater electrolysis.