Heterostructured NiS/Co₃S₄/Ni₃S₂ Nanomaterials for Urea Oxidation-Assisted Hydrogen Production

Compared with the oxygen precipitation reaction (OER), the theoretical application of urea oxidation reaction (UOR) with a smaller potential is more conducive to achieve H 2 release, showing a strong application prospect in the field of wastewater treatment. However, the efficiency of the traditional nickel foam-based catalyst is still subject to the following two factors: the high oxidation potential of Ni 3+ and the uncertainty of the oxidation and reduction active sites. Here, with the advantage of two-dimensional sheet porous high surface area, a Ni(OH) 2 nanosheet was prepared by depositing ZIF-67 to inhibit the formation of Ni 3+ and maximize the space utilization. Then, the NiS/Co 3 S 4 /Ni 3 S 2 nano heterostructure was constructed to improve the interface electronic structure and optimize the adsorption energy of the intermediates via in situ vulcanization. The NiS shell on the surface of the catalyst provides sufficient reaction sites for the catalytically active substance NiOOH generated during the UOR at a lower oxidation potential. At a current density of 50/100 mA cm –2, the overpotential is only 1.330/1.340 V while maintaining the catalytic durability for 20 h. At the same time, the NiS/Co 3 S 4 /Ni 3 S 2 /NF nano heterostructure material shows good urea degradation performance and stability, which provides the possibility of degradation and treatment of industrial, agricultural, and domestic wastewater containing urea.