Optimization of Mo doping in Ni-MOF for enhanced green hydrogen production via alkaline water electrolysis

Ni-based metal-organic frameworks (Ni-MOFs) have attracted significant attention as electrocatalysts for electrochemical water splitting due to their tunable structure and high surface area. In this study, the catalytic performance of Ni-MOFs was enhanced through Mo-doping at varying concentrations. Three Mo-doped Ni-MOFs were synthesized via a solvothermal method by in situ addition of Mo salt at molar ratios of 10 %, 20 %, and 30 %. Mo incorporation effectively tuned the d-band center of Ni, thereby improving the hydrogen evolution reaction (HER) activity. The Ni-MOF/Mo20 exhibited the best performance, featuring a 3D flower-like morphology composed of stacked 2D nanosheets. It achieved a low overpotential of 185 mV at 10 mA cm⁻² and a small Tafel slope of 58 mV dec⁻¹. Additionally, the overpotentials at higher current densities remained moderate—217 mV and 246 mV at 50 and 100 mA cm⁻², respectively. The enhanced performance is attributed to the increased density of electrochemically active sites and reduced charge transfer resistance resulting from Mo doping. These findings underscore the potential of Mo-doped Ni-MOFs as efficient electrocatalysts for HER applications.