NiS/MoS 2 nanoneedle heterostructures for enhanced hydrogen evolution and urea-assisted water splitting

Abstract The integration of the hydrogen evolution reaction (HER) with the urea oxidation reaction (UOR) offers an energy-saving route for hydrogen production, yet developing non-precious, efficient, and highly stable bifunctional electrocatalysts remains challenging. Herein, we report a NiS/MoS 2 heterostructure composed of vertically aligned nanoneedles directly grown on nickel foam via a facile one-pot hydrothermal method. The catalyst’s uniqueness lies in the synergistic interplay between its nanoneedle-array morphology and the well-defined heterointerface, which promotes directional electron migration along the nanoneedles and across the junction, lowers reaction energy barriers, and activates abundant catalytic sites. Benefiting from this rational design, the NiS/MoS 2 electrode exhibits an ultralow overpotential of 242 mV at 1000 mA cm −2 for HER. Density functional theory (DFT) calculations reveal that interfacial electron redistribution enhances water dissociation and optimizes the adsorption energies of key intermediates. In addition to superior HER activity, the catalyst also outperforms both pristine NiS and benchmark RuO 2 for UOR. When integrated into a HER||UOR electrolyzer, the NiS/MoS 2 ||NiS/MoS 2 couple requires only 1.36 V to achieve 10 mA cm −2 , significantly lower than conventional water electrolysis, and demonstrates excellent long-term stability over 80 h with negligible degradation, as confirmed by post-electrolysis characterization. This work presents a robust and high-performance bifunctional electrocatalyst and provides valuable insights for the rational design of heterostructure materials toward energy-efficient hydrogen production.