title: Band-gap manipulations of monolayer graphene by phenyl radical adsorptions: a density functional theory study.
abstract: Phenyl radical (Ph˙) adsorption on monolayer graphene sheets is used to investigate the band-gap manipulation of graphene through density functional theory. Adsorption of a single Ph˙ on graphene breaks the aromatic π-bond and generates an unpaired electron, which is delocalized to the ortho or para position. Adsorption of a second radical at the ortho or para position saturates the radical by electron pairing and results in semiconducting graphene. Adsorption of a second radical at the ortho position (ortho-ortho pairing) is found to be more favorable than adsorption at the para position (ortho-para pairing), and the ortho-ortho pairing has stronger effects on band-gap opening compared with ortho-para pairing. Adsorption of even numbers of Ph˙ on graphene by ortho-ortho and ortho-para pairings, in general, increases the band gap. Our study shows promise of band-gap manipulation in monolayer graphene by Ph˙ adsorption, leading to potential wider applications of graphene.
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 639798 (Singapore).
authors.forename: Lin
authors.initials: L
authors.lastname: Huang
authors.forename: Mahasin Alam
authors.initials: MA
authors.lastname: Sk
authors.forename: Peng
authors.initials: P
authors.lastname: Chen
authors.forename: Kok Hwa
authors.initials: KH
authors.lastname: Lim
keywords: band-gap manipulation; density functional calculations; graphene; phenyl; radicals