Crystalline–Amorphous Ni₃S₂–NiMoO₄ Heterostructure for Durable Urea Electrolysis-Assisted Hydrogen Production at High Current Density

Developing bifunctional catalysts with good performance at a high current density for the urea oxidation reaction (UOR) and the hydrogen evolution reaction (HER) can effectively relieve the severe environmental and energy pressures. Herein, amorphous NiMoO4 decorated Ni3S2 grown on nickel foam (Ni3S2–NiMoO4/NF) is prepared to accelerate UOR and HER. The crystalline–amorphous heterostructure could regulate the interfacial electron structure to reduce the electron density near Ni3S2 for optimizing UOR and HER. The decoration of NiMoO4 enhances its anti-poisoning ability for CO-intermediate species to show good stability at high current densities. Meanwhile, the nano-/microstructure with high hydrophilicity improves mass transfer and the accessibility of electrolyte. Driving high current densities of ±1000 mA cm–2, it merely needs 1.38 V (UOR) and −263 mV (HER). For urea electrolysis, it can deliver 1000 mA cm–2 at 1.73 V and stably operate at 500 mA cm–2 for 120 h. Therefore, this study provides new ideas for durable urea electrolysis-assisted H2 production.