In situ growth and interfacial reconstruction of Mo-doped Ni₃S₂/VO₂ as anti-corrosion electrocatalyst for long-term durable seawater splitting

Developing highly efficient and durable electrocatalysts for seawater splitting is critical but remains challenging. In this study, a novel and cost-effective Mo-Ni₃S₂/VO₂ catalyst was synthesized on nickel foam via a facile one-pot hydrothermal method. Comprehensive material characterization and theoretical analysis revealed that Mo and VO₂ modulate the electronic environment of Ni₃S₂, which enhances active sites and accelerates electron transfer. These synergistic effects allow Mo-Ni₃S₂/VO₂ to function as an excellent bifunctional catalyst for overall water electrolysis, achieving low cell voltages of 1.52 and 1.54 V at 10 mA cm⁻² in fresh water and seawater splitting, respectively. In situ analysis indicates that V cation leaching promotes the electro-oxidation reconstruction of Mo-Ni₃S₂/VO₂ to form Mo-Ni₃S₂/NiOOH heterointerface that significantly enhances OER activity and durability. Notably, the in situ formation of a dual anionic layer of VO₄³⁻ and SO₄²⁻ ions on the electrode surface repels Cl⁻ ions, thereby reducing electrode corrosion during seawater oxidation. The Mo-Ni₃S₂/VO₂ catalyst exhibits outstanding durability in seawater splitting over 1500 h at 100 mA cm⁻² and maintains appreciable stability under harsh conditions for 200 h.