Using density functional theory calculations, we investigate sensing mechanism of C-doped hexagonal boron nitride (h-BN) nanosheets toward NO and NO2 molecules. The results indicate that C-doping induces a large spin density and electron density redistribution in h-BN, which leads to improved adsorption energy of NO and NO2. The adsorption of NO and NO2 is able to alter significantly electronic structure of C-doped h-BN nanosheets as evidenced by relatively large variation in the band gap values. Moreover, the application of an external electric field can avoid the strong adsorption of NO and NO2 molecules over C-doped h-BN sheets. Compared to NO and NO2, the adsorption of CO, CO2, H2O or NH3 on C-doped h-BN sheets is remarkably weaker, suggesting that the sensing of NO and NO2 can be performed selectively in the presence of these molecules. Therefore, C-doped h-BN nanosheets can be viewed as promising and sensitive room-temperature sensors for NO and NO2 molecules.
