Fe/P Dual-Doped NiMoO ₄ with Hierarchical Structure for Urea Electrolysis-Assisted Hydrogen Production

The urea oxidation reaction (UOR) presents a sustainable pathway for energy-saving hydrogen production by replacing the sluggish oxygen evolution reaction (OER) in water electrolysis. However, developing efficient and stable UOR catalysts remains challenging. NiMoO 4 has emerged as a highly efficient UOR catalyst due to its synergistic intermetallic interactions and tunable electronic structure. Leveraging heteroatom doping, we engineered an Fe,P-codoped NiMoO 4 nanosheet array anchored on nickel foam (Fe,P-NiMnO 4 /NF) with dandelion-like hierarchical architecture via a facile hydrothermal-phosphorization approach. Systematic characterization demonstrates that Fe doping creates a porous hierarchical structure, facilitating mass transport and exposing abundant active sites, while P doping simultaneously optimizes the electronic configuration and enhancing hydrophilicity, leading to an expanding electrochemical active surface area. The resulting catalyst exhibits exceptional performance, achieving a current density of 100 mA cm –2 at just 1.345 V (vs RHE) for UOR, alongside a low HER overpotential of 270 mV at the same current density. When employed in a two-electrode overall urea splitting (OUS) system, it delivers 100 mA cm –2 at a cell voltage of 1.6 V with outstanding long-term stability of 50 h. This work introduces a design strategy for high-efficiency electrocatalysts in energy-efficient hydrogen production through urea-assisted electrolysis.