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Band-Gap Manipulations of Monolayer Graphene by Phenyl Radical Adsorptions: A Density Functional Theory Study



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 (orthoortho pairing) is found to be more favorable than adsorption at the para position (orthopara pairing), and the orthoortho pairing has stronger effects on band-gap opening compared with orthopara pairing. Adsorption of even numbers of Ph. on graphene by orthoortho and orthopara 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.

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