title: Effects of edge oxidation on the stability and half-metallicity of graphene quantum dots.
abstract: A comprehensive first-principles theoretical study of the electronic properties and half-metallic nature of zigzag edge-oxidized graphene quantum dots (GQDs) is carried out by using density functional theory (DFT) with the screened exchange hybrid functional of Heyd, Scuseria and Ernzerhof (HSE06). The oxidation schemes include -OH, -COOH and -COO groups. We identify oxidized GQDs whose opposite spins are localized at the two zigzag edges in an antiferromagnetic-type configuration, showing a spin-polarized ground state. Oxidized GQDs are more stable than the corresponding fully hydrogenated GQDs. The partially hydroxylated and carboxylated GQDs with the same size exhibit half-metallic state under almost the same electric-field intensity whereas fully oxidized GQDs behave as spin-selective semiconductors. The electric-field intensity inducing the half metal increases with the length of the partially oxidized GQDs, ranging from M=4 to 7.
authors.affiliation: College of Chemistry, Key Laboratory of Green Chemistry and Technology in Ministry of Education, Sichuan University, Chengdu 610064 (P. R. China).
authors.forename: Meilian
authors.initials: M
authors.lastname: Zhao
authors.forename: Feng
authors.initials: F
authors.lastname: Yang
authors.forename: Ying
authors.initials: Y
authors.lastname: Xue
authors.forename: Dan
authors.initials: D
authors.lastname: Xiao
authors.forename: Yong
authors.initials: Y
authors.lastname: Guo
keywords: density functional theory; electronic properties; graphene; half-metallic nature; quantum dots