▎ 摘　　要

The reduction of molecular dinitrogen (N-2) to ammonia (NH3) under mild conditions is attractive due to the wide application of ammonia. In this work, we systematically investigated a series of single metal atoms including Sc to Zn, Mo, Ru, Rh, Pd and Ag anchored on defective graphene sheets for the N-2 reduction reaction (NRR) by density functional theory computations. Our calculations revealed that single Mo embedded on nitrogen doped divacancy 555-777 graphene exhibits excellent catalytic performance for the NRR, with low overpotentials of 0.32 V for MoC1N2@555-777 graphene and 0.41 V for MoN3@555-777 graphene. In particular, the removal of produced ammonia from the catalyst surface is a rapid process with a free energy change of less than 0.50 eV. Our study provides a useful guideline for further developing highly effective SACs based on defective graphene for electrochemical reduction reactions.