Density Functional Theory Study of O2 and NO Adsorption on Heteroatom-Doped Graphenes Including the van der Waals Interaction

On the basis of the PBE-D2 calculation that empirically includes van der Waals interaction to the standard GGA approximation of Perdew, Berke, and Ernzerhof, we have investigated the adsorption of paramagnetic O-2 and NO on pristine, N-doped, and P-doped graphene. We found that the van der Waals interaction makes an important contribution to the physisorption energy and to the adsorption geometry of these gases in pristine and N-doped graphene. A detailed band-structure calculation shows that the electrostatic interaction due to charge transfer is also important, causing their adsorption on 2N-doped graphene to be appreciably stronger than that on pristine graphene or 1N-doped graphene. In the case of the adsorption of two molecules on 2N-doped graphene, spins of two adsorbed molecules couple differently depending upon the kind of gas molecules. Meanwhile, chemisorption of two O-2 atoms leaves the 2P-doped graphene a nonmagnetic semiconductor, while adsorption of two NO molecules turns the system into a magnetic semiconductor.