▎ 摘　　要

Considering the pivotal role of ammonia in the modern chemical industry, designing effective catalysts for the N-2-to-NH3 conversion stimulates great research enthusiasms. In this work, by means of density functional theory calculations, we systematically investigated the electrocatalysis of six-coordinated transition metal atom anchored graphene for nitrogen fixation. The free energy analysis shows that the ZrN6 configuration has a good activity toward ammonia synthesis under overpotential of 0.51 V. According to the electron transfer analysis, ZrN6 site plays a bridging role in charge transfer between the functional graphene and the reactant. Furthermore, the presence of N-6 coordination increases the electron accumulation on the NNHx intermediates, which weakens the intermolecular N-N bond, reducing the thermodynamic barrier of protonation process. This work provides a basic understanding of the interaction between transition metal and the adjacent coordination in tuning the reactivity.