Molecular adsorption in graphene with divacancy defects

We have investigated theoretically the adsorption of molecules onto graphene with divacancy defects. Using ab initio density-functional calculations, we have found that O₂, CO, N₂, B₂, and H₂O molecules all interact strongly with a divacancy in a graphene layer. Along with a complex geometry of the molecule-graphene bonding, metallic behavior of the graphene layer in the presence of CO and N₂ molecules has been found with a large density of states in the vicinity of the Fermi level suggesting an increase in the conductivity. The adsorption of N₂ is particularly interesting since the N atoms dissociate in the vicinity of the defects and take the place where the missing C atoms of the divacancy used to sit. In this way, the defected graphene structure is healed geometrically, and at the same time doped with electron states.