Sulfur-Coordinated Transition Metal Atom in Graphene for Electrocatalytic Nitrogen Reduction with an Electronic Descriptor.

Abstract

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-S4-G-SACs) are reported for nitrogen reduction under ambient condition. It shows that nine TM-S4-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-S4-G-SACs have better catalytic activity than those with nitrogen coordination. Particularly, the catalytic activity of TM-S4-G-SACs and the adsorption energy of intermediate NH2* conform to a volcano-type correlation, which can be described by a universal electronic descriptor φ, 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.