▎ 摘　　要

We investigate the adsorption effects of environmentally polluting or toxic gas molecules (NO, NO2, CO, and CO2) and abundant gas molecules in air (O-2 and N-2) on the energetics and electronic properties of boron (B)- and nitrogen (N)-doped monolayer graphenes by first-principles electronic-structure calculation. We find that only NO and NO2 molecules can chemically bind on B-doped monolayer graphene, while the other four types of molecules bind with much smaller adsorption energies. In the case of N-doped monolayer graphene, all six types of molecules bind with small adsorption energies. Scanning tunneling microscopy (STM) images are simulated, and NO and NO2 molecules on B-doped graphene are found to be detectable by using STM methods. The electron transport properties of B-doped graphene with and without NO and NO2 molecules are investigated, and the electrical conductances are found to show sharp reductions by as much as 30% and 15% upon the adsorption of the NO and NO2 molecules, respectively. Furthermore, the adsorption of NO and NO2 molecules on B-doped graphene can give rise to charge transfer between the NO and NO2 molecules and the graphene, and thereby the work functions of B-doped graphene vary depending on the type of adsorbate. Our theoretical findings indicate that B-doped graphene is a good candidate for sensor device materials for detecting only NO and NO2 molecules in air. (C) 2018 The Japan Society of Applied Physics