Hetero-structured NiMoO4/Ni3S4/MoS2 pompons decorated nickel foam electrode for high-efficient urea and urine electrolysis

In search of efficient electrolytic materials for hydrogen fuel production while realizing sewage denitrification, a unique heterostructure composed of the NiMoO4, Ni3S4 and MoS2 phases with multiple interfaces was grown on nickel foam (NF) by vulcanizing the NiMoO4 precursor. The obtained NF/NiMoO4-S possesses pompon-like morphology and abundant pores, significantly different from its precursor. Precisely due to this multi-phase, multi-interface, and highly opened porous structure, NF/NiMoO4-S exhibits outstanding electrochemical performance in terms of superior activity and selectivity, appropriate kinetics, high charge transfer efficiency and robust durability. In urea media, NF/NiMoO4-S requires a low HER overpotential of 73 mV (10 mA cm−2) and a small potential of 1.382 V for UOR (50 mA cm−2) respectively. When assembled into a whole-cell electrolyzer, the voltage (50 mA cm−2) is 1.55 V, much lower than that of water electrolyzer. Attractively, in the human-urine medium, no significant activity degradation was observed on NF/NiMoO4-S. Experiments have also demonstrated an excellent durability of the obtained NF/NiMoO4-S catalyst either in urea or urine condition. This work provides a simple and energy-saving idea for the design and preparation of practical urea electrolytic materials.