Double-atom catalysts: transition metal dimer-anchored C ₂N monolayers as N ₂ fixation electrocatalysts

Abstract

By first-principles computations, we investigated the electrocatalysis of transition metal atom-anchored C ₂N monolayers (TM _x@C ₂N, x = 1 or 2) for N ₂ fixation and proposed that Mo ₂@C ₂N is a promising electrocatalyst for the reduction of N ₂ to NH ₃.

Abstract

Nitrogen fixation is one of the most essential processes in chemistry. Developing more effective nitrogen fixation systems to catalyze the reaction under mild conditions is one of the most attractive but long-standing challenges. In this work, by means of first-principles computations, we systematically investigated the catalytic performance of transition metal atom-anchored C ₂N monolayer electrocatalysts (TM _x@C ₂N, x = 1 or 2; TM = Ti, Mn, Fe, Co, Cu, Mo, Ru, Rh, Pd, Ag, Ir, Pt, or Au) for N ₂ fixation. The natively N edged uniform holes could fix the TM atoms firmly in TM–N _x configurations, which is beneficial for the N ₂ fixation. Among them, Mo ₂@C ₂N exhibits the best catalytic performance for the reduction of N ₂ to NH ₃ with a maximum free energy change of 0.41 eV and an energy barrier of 0.51 eV, indicating that Mo ₂@C ₂N is a promising catalyst with high catalytic activity for the reduction of N ₂ to NH ₃. We believe that this work could provide a new idea for the design of N ₂ fixation catalysts and shed light on C ₂N monolayers as excellent substrates for catalysis.