Department of Chemistry, Yazd University, Yazd, Iran
The adsorptions of some mono and polyatomic gases on graphene nanoflake surfaces are investigated. Graphene nanoflake surface has been modeled and a suitable model for the graphene surface is found among a set of 2, 4, 7, and 19 hexagonal rings. State-of-the-art methods of density functional theory have been used in the present work. The adsorption energies and equilibrium distances have been calculated for a variety of mono and polyatomic gases such as Ar, O2, CO2, and CS2 gases for all possible orientations. Three highly symmetric adsorption sites on the surface are studied in the present work: atom-site, hollow-site, and bridge-site. For the monoatomic gases, the hollow-site and for polyatomic gases of CO2 and CS2, bridge-site are found to be more favorable than other sites. The best orientation for the studied polyatomic gases is found to be parallel. Results are compared with the available experimental data.