Methyl radical addition to the surface of graphene nanoflakes: A density functional theory study

Abstract

The interaction and reaction of methyl radical (CH3) with polycyclic aromatic hydrocarbons (PAHs) have been investigated by means of density functional theory (DFT) to systematically elucidate the binding nature of CH3 to graphene nanoflakes. PAHs with n = 4–37, where n indicates the number of benzene rings, were chosen as graphene nanoflakes. The activation energies for the addition of CH3 to the graphene surface were found to be almost constant, with values in the range 13.0–15.0 kcal/mol at the CAM-B3LYP/6-311G(d,p) level, for all PAHs. The binding energies between CH3 and the graphene surfaces were slightly dependent on the size (n): 1.0–4.2 kcal/mol. The absorption spectra showed that a long tail is generated in the low-energy region after CH3 addition to the graphene surfaces. The electronic states of the CH3-added graphenes were discussed on the basis of theoretical results