In situ growth of MOF-derived ultrafine molybdenum carbide nanoparticles supported on Ni foam as efficient hydrogen-evolution electrocatalysts

Abstract

The design of a universal synthetic strategy for long-term durable transition metal carbide catalysts with a controllable nanostructure and sufficient active sites for the hydrogen evolution reaction is challenging. Herein, the in situ growth of Mo-containing MOFs was achieved on three-dimensional (3D) nickel foam (NF) through the conversion of pre-deposited bimetal hydroxide/oxide nanosheets (Mo and Co). After pyrolysis, ultrafine Mo carbide nanoparticles encapsulated in cobalt and nitrogen-doped carbon layers were obtained. The ultrafine metal carbide nanoparticles favored the exposure of active sites, the in situ growth enhanced the binding between catalysts and substrate, and the cobalt and nitrogen-doped carbon layer facilitated charge transfer. The Mo_xC electrode showed a current of 10 mA cm⁻² at an overpotential of 33.5 mV under alkaline conditions, which was 6 mV lower than that of the 20% Pt/C/NF electrode. The W_xC electrode was also prepared. This work highlights a novel universal strategy to synthesize metal carbide electrodes.