Cobalt-Doping in Molybdenum-Carbide Nanowires Toward Efficient Electrocatalytic Hydrogen Evolution

Efficient hydrogen evolution reaction (HER) over noble‐metal‐free electrocatalysts provides one of the most promising pathways to face the energy crisis. Herein, facile cobalt‐doping based on Co‐modified MoOx–amine precursors is developed to optimize the electrochemical HER over Mo2C nanowires. The effective Co‐doping into Mo2C crystal structure increases the electron density around Fermi level, resulting in the reduced strength of Mo–H for facilitated HER kinetics. As expected, the Co‐Mo2C nanowires with an optimal Co/Mo ratio of 0.020 display a low overpotential (η10 = 140 and 118 mV for reaching a current density of –10 mA cm−2; η100 = 200 and 195 mV for reaching a current density of –100 mA cm−2), a small Tafel slope (39 and 44 mV dec−1), and a low onset overpotential (40 and 25 mV) in 0.5 m H2SO4 and 1.0 m KOH, respectively. This work highlights a feasible strategy to explore efficient electrocatalysts via engineering on composition and nanostructure. Cobalt‐doping into Mo2C increases the electron density of Mo and optimizes the electrocatalytic hydrogen evolution over Mo2C nanowires. With an optimal Co/Mo ratio, the Co‐Mo2C nanowires exhibit high activity and good stability in both acidic and basic electrolytes, performing among the best of current noble‐metal‐free electrocatalysts.