Adsorption mechanism of different toxic gases onto pristine BNC2 and Al-doped BNC2 monolayers.

Abstract

Graphene-based ternary BNC materials have been widely explored for the fabrication of gas sensors because of their various two-dimensional conjugated structures, high conductivity and large specific surface areas. To understand the essential physics and gas sensing properties, we focus on a sheet with equal concentration of C and BN, i.e. a BNC2 sheet. Using density functional theory, we have explored the effects of doping of an aluminium (Al) atom on the structural and electronic properties of a ternary BNC monolayer. We have studied the adsorption mechanism of various gas molecules such as CO, CO2, NO, NO2, SO2, and SO3 on BNC2 and Al@BNC2 MLs. Doping of the Al atom in BNC2 changes the structural as well as electronic properties of the host dramatically. The large-sized Al atom protrudes out from the BNC2 ML. The induced defects due to doping of the Al atom in BNC2 reduce the band gap of the BNC2 ML and enhance the reactivity of the BNC2 ML. The adsorption of CO, CO2, NO, NO2, SO2, and SO3 gas molecules shows higher interaction towards the Al@BNC2 ML as compared to the BNC2 ML. Among all the gas molecules, the maximum interaction of NO2 gas molecules is found with the Al@BNC2 ML. Adsorbed gas molecules act as charge acceptors from both the MLs. The improved conductivity of the Al@BNC2 ML as compared to BNC2 with the adsorption of gas molecules offers the basis for the development of ternary BNC-based gas sensors.