▎ 摘　　要

Graphene nanoflakes used for detecting air pollutants are extremely needed for the sake of environmental protection. We investigated the Freon gas, R22, belonging to the group of Hydrochlorofluorocarbons considered to be very dangerous, due to their role in destructing of layer, and discussed the adsorption of R22 on the surface of pristine, one Al-atom and two Al-atoms doped Graphene Nanoflakes (GNFs). Besides, we have studied theoretically the geometrical optimization, electronic properties and adsorption of undoped and doped Graphene Nanoflakes. All calculations are based on the density functional theory (DFT). Results show that adding one atom or two atoms of aluminum to GNFs causes a big decrease in the energy gap; at the adsorption of Freon R22 molecules by two Al-atoms doped GNFs, the structure becomes less gas-sensitive than one Al-atom doped GNFs. The band gaps, density of states (DOS), dipole moments, total energies, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies have been calculated for undoped and doped with Al GNFs either with or without the Freon R22 gas molecules.