Robust corrosion resistance of carbon-coated nickel-molybdenum catalyst for efficient and ultra-stable industrial-scale seawater splitting

The rational design of corrosion-resistant, bifunctional electrocatalysts for industrial seawater splitting, and a comprehensive understanding of catalytic mechanisms, remains a challenge. Herein, a novel carbon-coated Ni₄Mo/MoO₂ heterostructure (Ni₄Mo/MoO₂/C) is fabricated, exhibiting excellent activity and ultra-durability for overall seawater splitting. Theoretical studies indicate that the heterointerface optimizes the d‐band center, facilitates intermediate adsorption/desorption, lowers the reaction energy barrier, and enhances catalytic performance. In situ and ex situ characterizations reveal dynamic surface reconstruction mechanisms, forming Ni(OH)₂ and NiOOH active phases during the HER and OER processes. Additionally, the self-formation of a Cl⁻-repelling MoO₄²⁻ layer and a porous carbon forms a dual protective barrier that significantly enhances OER selectivity and mitigates Cl⁻-induced corrosion. In alkaline seawater, the catalyst achieves 100 mA cm⁻² at low overpotentials of 49 mV for HER and 322 mV for OER. Furthermore, a Ni₄Mo/MoO₂/C-based seawater electrolyzer shows superior stability over 2000 h at 500 mA cm⁻². An anion exchange membrane water electrolyzer utilizing Ni₄Mo/MoO₂/C enables voltages of 1.78 and 1.95 V at 0.5 and 1.0 A cm^–2, respectively, highlighting the strong potential of the catalyst for industrial-scale hydrogen production.