Improving the catalytic activity of two-dimensional Mo2C for hydrogen evolution reaction by doping and vacancy defects

Molybdenum carbide (Mo 2 C) has high catalytic activities toward electrocatalytic hydrogen evolution reaction (HER) owing to its high surface activity and electrochemical properties. However, the defects modification of Mo 2 C, which plays an important role in the HER activity, is relatively scarce in the theoretical research. Herein, in this work, based on first-principles calculations, we screen the influences of vacancies, nonmetal doping (X C/T , X = N, O, F, P and S) and metal substitutional doping (Y Mo , Y = Re and W) on HER of two-dimensional Mo 2 C. The results reveal that vacancies of Mo 6 C (0.02 eV) and Mo 3 C (0.22 eV), substitutional dopants of O C , S C , Re Mo (−0.33∼0.08 eV) and adsorptive dopants of N T , F T , P T , S T (−0.26∼0.14 eV) show enhanced catalytic activity with the absolute value of hydrogen adsorption free energy ( Δ G H ∗ ) smaller than 0.33 eV. A negative linear relationship is observed between Δ G H ∗ and d band center of transition metals in vacancies and metal dopants, but not in the configurations with nonmetal doping. The results provide more insight and guidance for the design of Mo 2 C electrocatalyst. • Nonmetal doping is formed more easily than metal substitution and vacancies in Mo 2 C. • The HER activity of Mo 2 C is signally improved by vacancies, substitutional and adsorptive dopants. • The catalytic behavior of Mo 2 C with vacancy defects and metal dopants is regulated by d band center.