The electrochemical reduction of N2 is an important industrial process, which offers an alternative route to the Haber-Bosch procedure for NH3 production. Here, by the method of first-principles calculations, we introduce Ni4 supported defective graphene (Ni4-Gr) as an efficient substrate to convert N2 into NH3. The enzymatic, alternating and distal mechanisms are investigated for N2 reduction to explore catalytic activity of Ni4-Gr surface. By analyzing the free energy diagrams, it is obtained that Ni4-Gr exhibits high catalytic performance for N2 reduction via the enzymatic pathway with an overpotential value of 0.50 V at normal temperature.
