▎ 摘　　要

Instead of the energy-intensive Haber-Bosch process, electrochemical nitrogen reduction reaction (NRR) is an exciting new carbon neutral technique for ammonia synthesis under ambient conditions. In this work, we investigated K-based electrocatalysts theoretically and demonstrated that K3Sb/graphene performs excellent activity and inhibits hydrogen evolution on alternating reaction pathway. The first hydrogenation step from N-2* to NNH* was found to be the most energetic and limiting step (0.61 eV). Graphene substrate plays the critical role to promote electronic conductivity between K3Sb and dinitrogen.