Theoretical calculation guided electrocatalysts design: Nitrogen saturated porous Mo2C nanostructures for hydrogen production

N-Doped Mo2C electrocatalysts combined with 3D porous structure effectively promote the kinetics of hydrogen evolution reaction. Theoretical calculation and experimental results reveal that the outstanding catalytic property relies on the high N content of Mo2C. When the surface of Mo2C is saturated with N atoms, Mo2C exhibits the best catalytic performance. [Display omitted] •N-doping concentration’s effect on catalytic property of Mo2C is first clarified.•The theoretical calculation is tight coupling with the experimental data.•When the surface N atoms are saturated, the catalytic performance is the best.•This strategy can be extended to other systems such as N-doped nickel carbide. Herein, based on our DFT-calculation, it is the first time to uncover the fact that the catalytic property of Mo2C is related to the concentration of doped-N atoms which plays a critical role in weakening the hydrogen absorption ability of Mo2C electrocatalysts and enhancing their catalytic property. When its surface is saturated with N atoms, Mo2C exhibits the best catalytic performance. Guided by this calculation result we highlight a strategy to synthesize Mo2C electrocatalysts whose surface is fully occupied by N atoms. Our electrocatalysts exhibit a low overpotential of 57 mV vs. RHE at the current density of 10 mA cm−2 and a small Tafel slope of 80 mV dec−1 in 1.0 M KOH for HER which is comparable with the commercial Pt-based electrocatalyst (overpotential of 39 mV at 10 mA cm−2, Tafel slope of 69 mV dec−1). Moreover, our strategy is regarded as a general method which is successfully extended and applied to improve other metal carbide electrocatalysts such as nickel carbide. This work will pave a way for the understanding and optimization of metal carbide electrocatalysts in HER.