Tailored synthesis of Zn–N co-doped porous MoC nanosheets towards efficient hydrogen evolution

Abstract

Developing non-precious metal catalysts with both high efficiency and long-term stability is the top priority for hydrogen evolution reactions (HER). Herein, we present a facile two-step method to synthesize Zn, N co-doped molybdenum carbide nanosheets (Zn–N–MoC–H NSs) by using bi-metal oxides of ZnMoO₄ as a unique precursor. Zn not only serves as a template to form a porous structure on MoC nanosheets during volatilizing at high temperatures, but also acts as a doping source for Zn doping in MoC. The N-containing carbon source realizes N doping of MoC. Benefitting from Zn, N co-doping and the porous nanosheet structure with a large electrochemical surface area, Zn–N–MoC–H NSs lead to enhanced HER activity in an acidic electrolyte (0.5 M H₂SO₄) with a low onset potential of −66 mV vs. RHE (1 mA cm⁻²), overpotential of 128 mV (10 mA cm⁻²), small Tafel slope of 52.1 mV dec⁻¹ and persistent long-term stability. Density functional theory calculations reveal that Zn, N co-doping can synergistically weaken the strong Mo–H bonding, improve absorbed hydrogen atom (H_ads) desorption and lead to faster HER kinetics. This study provides new insights into the use of Zn as a template and electronic regulator toward efficient catalysis and applications in energy storage and conversion.