Heteroatoms (-B-N-) doped graphene nanoflakes for the sensor mechanism of Carbon and Nitrogen dioxide adsorption: Approach from Theoretical Calculation

Density functional theory (DFT) calculations were carried out to study the adsorption of selected greenhouse gases (CO 2 and NO 2 ). The graphene doped with Heteroatoms (Boron and Nitrogen) atoms induces a surface character of electron delocalization arising from the sp 2 carbon of graphene to oxygen bond which aids high surface specificity. The orbital analysis, such as the density of states as well as frontier molecular orbital, has been studied indicating the kind of interaction (physisorption or chemisorption). It can be seen clearly that electrical conductivity is significantly enhanced by a decrease in energy gap (E.g.) which makes proposed surfaces suitable for the adsorption of CO 2 and NO 2 . A negative value for adsorption energy indicates that the process of adsorption is thermodynamically favoured. The B3LYP and PBE0 functional were employed for a benchmark study on adsorption energies. The adsorption energies (Eads) for the B3LYP functional ranged from -6.42 eV to -20.03 whereas -7.20eV to -30.90eV. the obtained adsorption energies (Eads) forPBE0 functional are more negative than that of the B3LYP functional, which reveals that, PBE0 functional shows better performance in the estimation of such weak interactions. The highest Eads of -30.90 eV was observed for GPQD_B for CO 2 adsorption. Thus, CO 2 is better adsorbed than NO 2 on the studied surface. Non-covalent interactions were observed for interaction between surfaces and probed molecules. The calculated results indicate that the graphene-doped surface is sensitive to CO 2 and NO 2 gas molecules.