Reduction-induced interface reconstruction to fabricate MoNi4-based hollow nanorods for hydrazine oxidation assisted energy-saving hydrogen production in seawater

Seawater electrolysis could address the water scarcity issue and realize the grid-scale production of carbon-neutral hydrogen, while facing the challenge of high energy consumption and chloride corrosion. Thermodynamically more favorable hydrazine oxidation reaction (HzOR) assisted water electrolysis is efficiency for energy-saving and chlorine-free hydrogen production. Herein, the MoNi alloys supported on MoO2 nanorods with enlarged hollow diameter on Ni foam (MoNi@NF) are synthesized, which is constructed by limiting the outward diffusion of Ni via annealing and thermal reduction of NiMoO4 nanorods. When coupling HzOR and hydrogen evolution reaction (HER) by employing MoNi@NF as both anode and cathode in two-electrode seawater system, a low cell voltage of 0.54 V is required to achieve 1,000 mA·cm−2 and with long-term durability for 100 h to keep above 100 mA·cm−2 and nearly 100% Faradaic efficiency. It can save 2.94 W·h to generate per liter H2 relative to alkaline seawater electrolysis with 37% lower energy equivalent input.