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

Wei, Zhaoqian, Hu, Xiao, Ning, Shunlian, Kang, Xiongwu, Chen, Shaowei
ACS sustainable chemistry & engineering 2019 v.7 no.9 pp. 8458-8465
catalysts, catalytic activity, copper, copper nanoparticles, electrical conductivity, electrochemistry, electron transfer, foams, foil, hydrogen production, molybdenum, nanoflowers, nickel, nitrogen content, pH, potassium hydroxide, pyrolysis, sulfuric acid, temperature
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/Mo₂C nanoribbons and nanoflowers on copper foam (MoₓC/Cu), copper foil, and nickel foam (MoₓC/Ni) are prepared via a two-step method: hydrothermal preparation of molybdenum precursors followed by pyrolysis at controlled temperatures. The MoₓC/Cu hybrids are found to exhibit an excellent catalytic activity, as compared to the MoₓC/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 H₂SO₄, and the corresponding Tafel slopes of 98 and 74 mV dec–¹, respectively. The electrocatalytic activity is also found to vary with the Mo²⁺/Mo³⁺ and N contents in the samples that impact the electrical conductivity and electron-transfer kinetics of the hydrogen evolution reaction. Results suggest that MoC/Mo₂C heterostructured materials supported on copper foam may be a viable candidate to catalyze hydrogen evolution reaction in a wide range of pH.