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 (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.
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