Synergistically engineering of amorphous-crystalline heterostructure and lattice defects on hierarchical NiCoSx/NF for efficient overall urea-assisted water splitting

• Published in: International journal of hydrogen energy 2024-11, Vol.92, p.324-332
• Main Authors: Li, Guang-Lan, Deng, Fei, Ma, Tian-Ge, Shi, Yu-Hui, Liao, Zi-Qi, Liu, Jia-Jun, Yan, Yang, Wang, Erdong
• Format: Article
• Language: English
• Subjects: Amorphous-crystalline heterojunction; Hydrogen evolution reaction; Lattice defects; Sulfurization; Urea oxidation reaction
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2024.10.234

Urea-assisted water electrolysis is a promising strategy for the high-efficiency hydrogen production due to the more favorable anodic thermodynamic potential of urea oxidation reaction (UOR) than that of oxygen evolution reaction (OER). However, the kinetics of UOR is sluggish and thereby the fabrication of UOR catalyst which also possesses cathodic hydrogen evolution reaction (HER) catalytic performance is ascribed to be the paramount bottleneck due to the hard simultaneous satisfaction between UOR and HER performance metrics. Herein, a hierarchical amorphous-crystalline heterogeneous NiCoSx nanosheet with rich lattice defects grown on nickel foam (NiCoSx/NF) catalyst was proposed via scalable solvothermal method for overall urea-assisted water electrolysis. The NiCoSx/NF only needs an ultralow potential of 1.36 V to drive 100 mA cm−2 for UOR, exceeding that of OER for 220 mV, and an overpotential of 183 mV to obtain 100 mA cm−2 for HER. More importantly, the urea electrolyzer assembled with NiCoSx/NF as both cathode and anode could achieve 10, 100, and 500 mA cm−2 at battery voltages of 1.41 V, 1.55 V, and 1.75 V, respectively, with continuous working for 60 h. Experimental and density functional theory calculations reveal that the strong electronic interactions caused by heterojunctions and lattice defects exposed on the well-accessible NF surface result in the increased proportions of Ni3+ active sites and enhanced conductivity, which should be responsible for the superior UOR and HER performance. •NiCoSx nanosheets with Co3S4/Ni3S2/NiCo heterojunctions and rich defects grew on nickel foam.•NiCoSx/NF-based urea-assisted water splitting device show prominent catalytic activity and stability.•Heterojunctions and defects should be responsible for the superior performance of NiCoSx/NF.