Controlled synthesis of M-MnS/Ni3S2(M=Zr, Ce, Bi and V) nanoarrays on nickel foam for overall urea splitting

In this study, we developed Zr-doped MnS/Ni3S2 with heterogeneous nanosheets on foamed nickel through a straightforward one-step solvothermal process, aiming to find relatively low toxicity, efficient, robust, and highly selective electrodes for overall urea splitting. The electrochemical performance of the catalyst was assessed under alkaline conditions, demonstrating remarkably low potentials of 1.43 V and 1.38 V for urea oxidation reaction (UOR) at 100 mAcm(-2) and 10 mAcm(-2) and overpotentials of 103 mV for hydrogen evolution reaction (HER) at 10 mA cm(-2), along with a modest Tafel slope of 92 mV/dec. The catalyst also showed good stability over a 15-h test period. Comparative analysis indicated that our Zr-MnS/Ni3S2@NF catalyst outperformed competitors, largely because of the synergistic effects of heterojunction for MnS/Ni3S2 and the Zr doping. This strategy enhanced the conductivity of catalyst, optimized the electron configuration at reaction centres, and improved the Gibbs free energy of hydrogen production, thereby accelerating reaction dynamics and achieving high electrochemistry activity. Density functional theory (DFT) calculations further supported our findings, revealing that Zr doping increases the exposure of active Ni3S2 sites, optimizes Gibbs free energies of intermediates, and enhances intrinsic activity. Overall, this research offers valuable insights into the cooperative enhancement of electrochemistry performance, paving the way for advanced applications in urea splitting and beyond.