▎ 摘　　要

The adjacent chemical microenvironment of single metal atoms in heterogeneous catalysis is crucial to their chemical activity for various catalytic processes. Here, based on first-principles calculations, 25 single transition metal atom catalysts coordinated to sulfur species embedded in graphene (TM-S-4-G-SACs) are reported for nitrogen reduction under ambient condition. It shows that nine TM-S-4-G-SACs (TM = Mo, Sc, Cr, V, W, Ti, Nb, Mn, and Re) are promising nitrogen reduction catalysts with an optimal potential of -0.425 V. Meanwhile, 18 TM-S-4-G-SACs have better catalytic activity than those with nitrogen coordination. Particularly, the catalytic activity of TM-S-4-G-SACs and the adsorption energy of intermediate NH2* conform to a volcano-type correlation, which can be described by a universal electronic descriptor phi, defined by the electronegativity of the metal, adjacent coordinated atoms, and the valence electron occupancy. The above findings suggest the potential of sulfur-coordinated single metal atoms as electrocatalytic nitrogen reduction catalysts and an applicable descriptor to achieve optimal performance.