Figure 1.

Single and di-atom doping sites on the defected monolayered graphene sheet. Metal dopants are coordinated to the graphene atoms through N atoms. The metal dopants are represented in orange, carbon atoms in gray, and N atoms in blue. SAC corresponds to the doping site for the single metal dopants. For DACs, the dopant sites are named by two-letter symbols as derived from the initials of the vacancy sites. Here, DV denotes the divacancy site, TV for trivacancy, QV for quadvacancy, PV for pentavacancy, and HV for hexavacancy. In the case of DV and QV, three stable structural geometries are obtained, whereas for the other vacancy sites, only one configuration is found to be stable.