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

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 (Hads) 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.