Fig. 1 (a) Atomic structure of TM1N4/TM2 and (b) screening criterion for TM1N4/TM2 combination

Fig. 2 Gibbs free energy difference between N2 and NNH with the orange line at 1.08 eV Colorful figures are available on website

Fig. 3 Schematic reaction mechanisms Colorful figure is available on website

Fig. 4 Free energy diagrams and the corresponding configuration of the NRR intermediates on NiN4/Cr NRR mechanisms are (a) distal, (b) alternating and (c) enzymatic

Fig. 5 (a-c) Charge variation of the three moieties along the optimal pathway and (d) N-N bond length change in NRR along preferred pathway Moieties 1, 2, 3 represent the graphene substrate, active center, and NRR intermediates, respectively

Fig. S1 Comparison of binding energy and bulk cohesive energy of the selected complexes

Fig. S2 Free energy diagrams and the corresponding configuration of the NRR intermediates on NiN4/Mo NRR mechanisms are (a) distal, (b) alternating, and (c) enzymatic, respectively

Fig. S3 Free energy diagrams and the corresponding configuration of the NRR intermediates on NiN4/Ta NRR mechanisms are (a) distal, (b) alternating, and (c) enzymatic, respectively

Fig. S4 Free energy diagrams and the corresponding configuration of the NRR intermediates on Cr embedded nitrogen functionalized graphene NRR mechanisms are (a) distal, (b) alternating, and (c) enzymatic, respectively

Fig. S5 Free energy diagrams and the corresponding configuration of the NRR intermediates on Mo embedded nitrogen functionalized graphene NRR mechanisms are (a) distal, (b) alternating, and (c) enzymatic, respectively

Fig. S6 Free energy diagrams and the corresponding configuration of the NRR intermediates on Ta embedded nitrogen functionalized graphene NRR mechanisms are (a) distal, (b) alternating, and (c) enzymatic, respectively

Fig. S7 Free energy profiles of N2-to-NH3 conversion on the N vacancy

Fig. S8 Atomic configurations of the hydrogen adsorption on the nitrogen embedded in graphene after geometry optimization