Crystalline-Amorphous Ni 3 S 2 -NiMoO 4 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 NiMoO ₄ decorated Ni ₃ S ₂ grown on nickel foam (Ni ₃ S ₂ -NiMoO ₄ /NF) is prepared to accelerate UOR and HER. The crystalline-amorphous heterostructure could regulate the interfacial electron structure to reduce the electron density near Ni ₃ S ₂ for optimizing UOR and HER. The decoration of NiMoO ₄ 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 H ₂ production.