Dual-doping NiMoO4 with multi-channel structure enable urea-assisted energy-saving H2 production at large current density in alkaline seawater

Seawater electrolysis is an efficient method for producing carbon-neutral hydrogen; however, it is hindered by high energy cost and chlorine evolution reaction. In this study, we report Ru, P dual-doped NiMoO4 multichannel nanorods in-situ grown on nickel foam (Ru/P-NiMoO4 @NF), which can achieve chlorine-free hydrogen production by coupling seawater splitting with thermodynamically favorable urea oxidation. The Ru/P-NiMoO4 @NF exhibits bifunctional activity with working potentials of 0.23 V to deliver 3000 mA cm−2 for HER and 1.46 V to deliver 1000 mA cm−2 for UOR. The overall urea splitting system in the two-electrode electrolyzer require low voltage of 1.73 V to drive 500 mA cm−2, and demonstrate remarkable durability to keep above 100 mA cm−2 for 145 h. Density functional theory calculations reveal that dual-doping modulate the d-band center of catalyst, thus enhancing the adsorption of reactants and intermediates. This work provides information for designing catalysts for combing seawater splitting with urea purification.