The important role of surface charge on a new mechanism of nitrogen reduction.

The electrocatalytic nitrogen reduction reaction (NRR) is a green and sustainable approach for producing ammonia. Low-cost carbon-based materials are promising catalysts for the electrochemical NRR. Among them, Cu-N 4 -graphene is a unique catalytic substrate. Its catalytic performance for the NRR has remained unclear as N 2 can only be physisorbed on such a substrate. In this work, we focus on the influence of an electronic environment on the electrocatalytic NRR. DFT computations reveal that the NN bond can be effectively activated at a surface charge density of -1.88 × 10 14 e cm -2 on Cu-N 4 -graphene and further the NRR proceeds via an alternating hydrogenation pathway. This work offers a new insight into the mechanism of the electrocatalytic NRR and emphasizes the importance of environmental charges in the electrocatalytic process of the NRR.