Effect of side chain edge functionalization in pristine and defected graphene-DFT study.

The structural and electronic properties of edge-functionalized graphene sheets are systematically investigated utilizing Density Functional Theory (DFT). The functionalization includes alkyl, alkene, and seven different polyacetylene side chains as an alternative for a hydrogen atom in eight different kinds of graphene sheets. CH 3 and longer side chains functionalization have high stability and remains unaffected by increasing the size of the graphene sheet. The weak binding energy and large formation energy are observed for CH 2 , C 3 H 4 and C 5 H 6 functionalization in all eight different kinds of the graphene sheet. The high charge transfer from graphene to side chain having high σ bonds is interpreted by Voronoi deformation density (VDD) method. The delocalization of the graphene ring decreases in side chain functionalization and gets decreased further when the size of the graphene sheet is increased. The high alteration in aromaticity is illustrated by decrease in Para Delocalization Index (PDI) value with an increase in aromatic Fluctuation Index (FLU) value in weakly binded side chains. The decrease in Highest Occupied Molecular Orbital (HOMO) along with a decrease in band gap on the substitution of nine different side chains in both pristine and defected sheet is observed. Moreover, the decrease in electron accepting ability is observed for CH 3 , C 3 H 5 and C 5 H 7 functionalization in all kinds of graphene sheets, which is inferred from the decrease in Lowest Unoccupied Molecular Orbital (LUMO). [ABSTRACT FROM AUTHOR]