Tunable Ni/Fe-Mo carbide catalyst with high activity toward hydrogen evolution reaction

Cost-effective catalysts for hydrogen evolution reaction (HER) are attractive for sustainable production of H₂ fuel. Herein, a series of tunable Ni/Fe-Mo carbide catalysts have been synthesized via a sol-gel method coupling with a subsequent high temperature carbonization process. The amount of nickel and iron was tuned in the Mo₇/C precursors, accomplishing a favourable performance of noble-metal-free electrocatalysts for HER. As expected, the designed Ni₁₀Fe₄Mo₇/C catalyst displays an enhanced catalytic activity toward hydrogen production with an ultralow overpotential (η₁₀ = 110 mV) and striking kinetics (η_onset = 58 mV, k = 54 mV · dec^?1) in the alkaline electrolyte (1 M KOH), which are comparable to those of the commercial 20% Pt/C catalyst. Such excellent performance of Ni₁₀Fe₄Mo₇/C could be attributed to the high intrinsic activities of Ni-based alloys (NiMo₄) and Mo₂C, as well as to the lattice contraction in the Mo₂C unit cell, in accordance with its high electrochemical surface area (~133 m² · g^?1) and low charge-transfer resistance (~31.5 Ω) for the associated electrode.