Synergistic promotion and enhanced water splitting in Mn, Co, Ni-doped MoSe₂/Mo₂C heterostructures via doping and interface engineering

Two-dimensional transition metal dichalcogenides (TMDs) have attracted interest as efficient electrocatalysts for water splitting. Among them, molybdenum diselenide (MoSe₂) exhibits promising activity due to its exposed active edge sites and favorable electronic properties. However, its performance is restricted by an inert basal plane and low conductivity. To address these limitations, metal doping and interface engineering were employed to tailor the lattice, electronic, and surface characteristics of MoSe₂. In this study, Ni-, Co-, and Mn-doped MoSe₂ and molybdenum carbide (Mo₂C) heterostructures were synthesized via a hydrothermal method and characterized using XRD, SEM, XPS, TEM, and EDS. Ni-doped MoSe₂/Mo₂C demonstrated the best bifunctional electrocatalytic performance, with overpotentials of 470 mV for OER and 290 mV for HER, representinga 5%–30% improvement over Co- and Mn-doped samples and a 38%–53% enhancement compared to undoped MoSe₂/Mo₂C. The corresponding Tafel slopes of 159 mV/dec (OER) and 97 mV/dec (HER) indicated accelerated reaction kinetics. High double-layer capacitance and electrochemical surface area values confirmed the improved catalytic activity. These results demonstrate that metal doping and interface modulation significantly enhance the electrocatalytic efficiency, stability, and durability of MoSe₂/Mo₂C heterostructures, demonstrating Ni-doped MoSe₂/Mo₂C as a promising bifunctional catalyst for water splitting.