Enhancing the Overall Electrocatalytic Water-Splitting Efficiency of Mo₂C Nanoparticles by Forming Hybrids with UiO-66 MOF

For efficient electrocatalytic water-splitting, developing a nonprecious-metal-based stable and highly active material is the most challenging task. In this paper, we have devised a synthesis strategy for a hybrid catalyst composed of molybdenum carbide (Mo₂C) and a Zr-based metal–organic framework (MOF) (UiO-66) via the solvothermal process. Synergistic effects between Mo₂C and UiO-66 lead to a decrease in the hydrogen adsorption energy on the catalysts, and Mo₂C/UiO-66 hybrids offer excellent catalytic activity in an alkaline environment for water-splitting. Particularly, the optimized Mo₂C/UiO-66 hybrid, termed MCU-2 with 50:50 wt % of both components, displayed the best catalytic performance for both hydrogen and oxygen evolution reactions (HER/OER). It offered a small overpotential of 174.1 mV to attain a current density of 10 mA/cm² and a Tafel plot value of 147 mV/dec for HER. It also offered a low overpotential of around 180 mV to attain a current density of 20 mA/cm² and a Tafel plot value of 134 mV/dec for OER. Additionally, the catalyst was stable for over 24 h and ∼1000 cycles with a very minute shift in performance, and the electrolyzer indicates that a potential of ∼1.3 V is required to reach 10 mA/cm² current density. It can be inferred from the results that the Mo₂C/UiO-66 hybrid is a promising candidate as a nonexpensive and active catalyst for overall electrocatalytic water-splitting as the devised catalyst exhibits enhanced kinetics for both OER and HER, a more exposed surface area, faster electron transport, and enhanced diffusion of the electrolyte.