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. 2020 Feb 18;11:938. doi: 10.1038/s41467-020-14565-w

Fig. 1. The calculation models and results.

Fig. 1

a The geometric configurations of Mg embedded in graphene framework predominantly existing as single atoms coordinated with different numbers (from 1 to 4) of nitrogen atoms. The green, blue, and gray balls represent metal, N and C atoms, respectively. b Adsorption free energies of OOH as a function of that of OH for models of Mg, Al, and Ca coordinated with different numbers of pyridine nitrogen atoms embedded in graphene matrix. c Adsorption free energies of O versus that of OH for all models. d The two-dimensional volcano map about theoretical onset potential versus adsorption free energies ΔGOH* and ΔGOOH* on main group metal cofactors (M–N–C). e The zoomed-in view of the onset potential versus ΔGOH* in the region close to the performance ceiling of models and transition metal cofactors (TM–N4–C).