title: Surface Charge-Transfer Doping of Graphene Nanoflakes Containing Double-Vacancy (5-8-5) and Stone-Wales (55-77) Defects through Molecular Adsorption.
abstract: The adsorption of six electron donor-acceptor (D/A) organic molecules on various sizes of graphene nanoflakes (GNFs) containing two common defects, double-vacancy (5-8-5) and Stone-Wales (55-77), are investigated by means of ab initio DFT [M06-2X(-D3)/cc-pVDZ]. Different D/A molecules adsorb on a defect graphene (DG) surface with binding energies (ΔEb) of about -12 to -28 kcal mol-1. The ΔEbvalues for adsorption of molecules on the Stone-Wales GNF surface are higher than those on the double vacancy GNF surface. Moreover, binding energies increase by about 10 % with an increase in surface size. The nature of cooperative weak interactions is analyzed based on quantum theory of atoms in molecules, noncovalent interactions plot, and natural bond order analyses, and the dominant interaction is compared for different molecules. Electron density population analysis is used to explain the n- and p-type character of defect graphene nanoflakes (DGNFs) and also the change in electronic properties and reactivity parameters of DGNFs upon adsorption of different molecules and with increasing DGNF size. Results indicate that the HOMO-LUMO energy gap (Eg) of DGNFs decreases upon adsorption of molecules. However, by increasing the size of DGNFs, the Egand chemical hardness of all complexes decrease and the electrophilicity index increases. Furthermore, the values of the chemical potential of acceptor-DGNF complexes decrease with increasing size, whereas those of donor-DGNF complexes increase.
authors.affiliation: Department of Chemical Engineering, Birjand University of Technology, Birjand, P.O. Box 97175/569, Iran. shakourian@birjandut.ac.ir.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Shakourian-Fard
authors.affiliation: Chemistry and Chemical Engineering Research Center of Iran, Tehran, P.O. Box 14335-186, Iran. jamshidi@ccerci.ac.ir.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Jamshidi
authors.affiliation: Department of Chemistry, University of Missouri-Columbia, Columbia, MO, 65211, USA.
authors.forename: Ganesh
authors.initials: G
authors.lastname: Kamath
keywords: defects; donor-acceptor systems; graphene; noncovalent interactions; surface analysis