Surface-clean, phase-pure multi-metallic carbides for efficient electrocatalytic hydrogen evolution reaction

Abstract

The development of highly active, stable and low-cost non-noble metal catalysts for hydrogen evolution reaction (HER) is extremely imperative. Multi-metal based electrocatalysts have recently become an emerging class of hydrogen evolution reaction (HER) electrocatalysts due to their excellent electrical conductivity and synergistic effects from metal atoms. However, the relationship between the cation and its intrinsic electrocatalytic properties in multi-metallic electrocatalysts is still not clear. Herein, we report a facile method for the preparation of surface-clean, phase-pure bimetallic (or multi-metallic) carbides through the solid reaction between metal salts and carbon nanotubes under an inert atmosphere. These multi-metallic carbides include molybdenum-based carbides (Co₃Mo₃C and Fe₃Mo₃C), tungsten-based carbides (Co₆W₆C, Ni₆W₆C and Fe₆W₆C) and trimetallic carbides (Co_xFe_3−xMo₃C and Co_xFe_6−xW₆C). Based on the synergistic effect of the metal atoms, the catalytic activities of the resulting bimetallic and trimetallic carbides are significantly improved compared to that of the single-metal carbides. The catalytic activity of the metal carbides decrease in the order of Co-based > Ni-based > Fe-based and Mo-based > W-based. Among them, Co₃Mo₃C has an optimized catalytic activity, offering a current density of 10 mA cm⁻² at a low overpotential of 169 mV. Our study provides a controllable method for the preparation of the multi-metallic carbides and further justifies that the multi-metallic carbides are effective catalysts for HER.