Using dispersion-corrected density functional theory calculations, the adsorption behavior of NO and NO2 molecules is studied over B-doped and BN co-doped graphene sheets (BCmNn-Gr; m,n=0,1,2,3 and m+n=3). To examine practical gas sensing application and selectivity, the adsorption of H2O, CO and CO2 molecules is also studied on the BCmNn-Gr surfaces. It is found that the preferred adsorption site for the adsorption of these molecules is above the B atom due to accumulation of a local positive charge. Meanwhile, the incorporation of nitrogen atoms in BCmNn-Gr makes a substantial increase in the adsorption energies of NO and NO2, mainly due to the shift in the Fermi energy and electron (donor) concentration states of these surfaces. According to our results, the electronic structure of BC3-Gr, BC2N-Gr and BCN2-Gr is sensitive to NO and NO2 as evidenced by relatively large variation of the electronic structure as well as charge-transfer values. To address the curvature effect of BCmNn-Gr nanosheets on the adsorption and sensing properties of NO and NO2, the adsorption of these molecules is also investigated over B-doped and BN-codoped (6,6) carbon nanotubes. The calculations also indicate that BN co-doped graphene sheets can be used as an efficient and promising gas sensing material for detecting NO and NO2 molecules in the presence of H2O, CO and CO2.
