Supported Heterostructured MoC/Mo₂C Nanoribbons and Nanoflowers as Highly Active Electrocatalysts for Hydrogen Evolution Reaction

Development of low-cost and high-efficiency electrocatalysts for hydrogen evolution reaction is a critical step toward sustainable water splitting. Herein, in situ growth of heterostructured MoC/Mo 2 C nanoribbons and nanoflowers on copper foam (Mo x C/Cu), copper foil, and nickel foam (Mo x C/Ni) are prepared via a two-step method: hydrothermal preparation of molybdenum precursors followed by pyrolysis at controlled temperatures. The Mo x C/Cu hybrids are found to exhibit an excellent catalytic activity, as compared to the Mo x C/Ni and Cu foil counterparts, and the sample prepared at 750 °C stands out as the best among the series with a low overpotential of 169 mV to reach the current density of 200 mA cm –2 in 1 M KOH, and 194 mV in 0.5 M H 2 SO 4, and the corresponding Tafel slopes of 98 and 74 mV dec –1, respectively. The electrocatalytic activity is also found to vary with the Mo 2+ /Mo 3+ and N contents in the samples that impact the electrical conductivity and electron-transfer kinetics of the hydrogen evolution reaction. Results suggest that MoC/Mo 2 C heterostructured materials supported on copper foam may be a viable candidate to catalyze hydrogen evolution reaction in a wide range of pH.