Phase-Synergized NiS-MnS-MoS₂ Hybrid: An Efficient and Durable Electrocatalyst for Alkaline Urea Oxidation Reaction

In the context of developing ultra-efficient electrocatalysts for the urea oxidation reaction (UOR)-driven sustainable energy conversion and storage systems, this work presents a strategically designed two-step hydrothermal synthesis route for the fabrication of NiS-MnS-MoS₂, a multiphase hybrid material system with low crystalline features, a unique rod-like porous microstructure with inherent intercrystallite porosity, and S^2- ions-induced interphase synergism. The electrochemical assessment of the NiS-MnS-MoS₂ hybrid material demonstrates excellent redox reversibility, abundant electrocatalytically active surface sites, high electrocatalytic surface area (1316 cm² g^-1 at a scan rate of 10 mV s^-1), substantial turnover frequency (0.019 s^-1), extremely low Tafel slope (73 mV dec^-1), excellent charge transfer kinetics, and low interfacial resistance during electrocatalytic UOR in alkaline medium. The 20-fold increase in peak current density also affirms the excellent urea oxidation efficiency of the NiS-MnS-MoS₂ electrocatalyst. Furthermore, the NiS-MnS-MoS₂ electrocatalyst requires a much lower potential (∼420 mV) than the potential required for the highly competent oxygen evolution reaction (OER) and sustained a remarkable 32-h catalytic stability under continuous UOR operation. The incessant availability of active sites, high sulfide synergism favoring antipoisoning activity, high electronic conductivity, and facilitated active species generation for shallow urea adsorption support faster UOR kinetics under prolonged UOR operation. The optimized methodology underscores the importance of rational phase synergy and microstructural physiognomics in designing advanced non-noble electrocatalysts, which offers a promising path forward for integrating UOR-based energy modules into next-generation sustainable energy systems.