A single transition metal atom anchored on Nb 2 C as an electrocatalyst for the nitrogen reduction reaction.

Nitrogen (N 2 ) reduction to produce ammonia (NH 3 ) under milder conditions is attractive as NH 3 has been widely used in various fields. The electrocatalytic nitrogen reduction reaction (NRR) is considered to be a more moderate and green method for ammonia synthesis. Herein, using density functional theory (DFT) computations, we investigated the potential application of single-atom catalysts (SACs) toward the NRR, in which transition metal (TM, TM = Ti, V, Mn, Fe, Co, Y, Zr, Mo) atoms are supported on Nb 2 C (TM-Nb 2 C). Through our screening, Fe-Nb 2 C is highlighted from 8 candidate systems as the superior SAC for the NRR with a low limiting potential of -0.47 V. Meanwhile, a volcano plot between U L (NRR) and the ICOHP values of the N-H bond in *NH 2 is established to determine the optimal ICOHP values that can be used as a simple descriptor of the NRR performance of Fe-Nb 2 C.