Adsorption of molecular oxygen on doped graphene: Atomic, electronic, and magnetic properties

Adsorption of molecular oxygen on B-, N-, Al-, Si-, P-, Cr- and Mn-doped graphene is theoretically studied using density-functional theory in order to clarify if O-2 can change the possibility of using doped graphene for gas sensors, electronic, and spintronic devices. O-2 is physisorbed on B-, and N- doped graphene with small adsorption energy and long distance from the graphene plane, indicating the oxidation will not happen; chemisorption is observed on Al-, Si-, P-, Cr- and Mn-doped graphene. The local curvature caused by the large bond length of X-C (X represents the dopants) relative to C-C bond plays a very important role in this chemisorption. The chemisorption of O-2 induces dramatic changes of electronic structures and localized spin polarization of doped graphene, and in particular, chemisorption of O-2 on Cr- doped graphene is antiferromagnetic. The analysis of electronic density of states shows the contribution of the hybridization between O and dopants is mainly from the p or d orbitals. Furthermore, spin density shows that the magnetization locates mainly around the doped atoms, which may be responsible for the Kondo effect. These special properties supply a good choice to control the electronic properties and spin polarization in the field of graphene engineering.