Effects of gas adsorption on the stabilities, electronic structures, and scanning tunneling microscopy of graphene monolayers doped with B or N

Abstract

We investigate the adsorption effects of environmentally polluting or toxic gas molecules (NO, NO2, CO, and CO2) and abundant gas molecules in air (O2 and N2) 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.