Molybdenum Carbide Electro‐Converted from CO 2 and MoO 3 for Hydrogen Evolution Reaction

Abstract Molybdenum carbide (MoC/Mo 2 C), due to its unique noble‐like metallic electronic structure, high conductivity, and abundant surface‐active sites, exhibits promising catalytic performance for the hydrogen evolution reaction (HER). The directional and controllable synthesis of molybdenum carbide with specific phase composition is crucial for enhancing catalytic performance. This study employs a green and clean electrochemical method to achieve one‐step controllable synthesis of a dual‐phase MoC–Mo 2 C in molten salt. The electrolytic mechanism analysis reveals that MoO 3 reacts with molten salt components to form soluble molybdate. Subsequently, CO 3 2− and MoO 4 2− as the electroactive ions are co‐reduced, and then molybdenum carbide is in situ formatted at the cathode. By controlling the electrolysis temperature, the phase composition and morphology of molybdenum carbide are effectively regulated, yielding a feather‐like dual‐phase MoC–Mo 2 C catalyst. In a 1.0 M KOH solution, the dual‐phase MoC–Mo 2 C catalyst exhibits a superior HER activity. The low overpotential is only 118 mV at a current density of 10 mA cm −2 for HER. Furthermore, it exhibits excellent stability, with only a 34 mV overpotential increase at 10 mA cm −2 after 30 h. This study provides a novel strategy for the clean and resource‐efficient utilization of CO 2 to synthesize molybdenum carbide catalysts for high performance.