Modulating the electronic and magnetic structures of P-doped graphene by molecule doping

The adsorption of gas molecules on P-doped graphene (PG) was theoretically studied using density-functional theory in order to find the possibility of modulating electronic and magnetic ordering of graphene. H₂, H₂O, CO₂, CO, N₂ and NH₃ molecules are physisorbed, while NO, NO₂, SO₂ and O₂ molecules are strongly chemisorbed on PG through the formation of P-X (X = O, N, S) bonds. P dopant introduces global spin polarization into graphene with order of 1.05 μ(B). Chemisorption of NO₂ and SO₂ makes the spin polarization and projected density of states (PDOS) of molecules localized. NO also induces a partly localized spin state and O₂ an unpolarized system. Meanwhile, the systems of NO₂ and O₂ on PG are metallic, while NO and SO(2) on PG are half-metallic. Therefore, the properties of PG are strongly dependent on the types of molecules adsorbed, and the method of combining foreign atom doping followed by exposure to air is effective for the engineering of graphene.