title: Hybrid nanotube-graphene junctions: spin degeneracy breaking and tunable electronic structure.
abstract: Hybrid carbon nanostructures have attracted enormous interest due to their structural stability and unique physical properties. Geometric and physical properties of a carbon nanotube (CNT)-graphene nanoribbon (GNR) hybrid system were investigated via first-principles density functional theory (DFT) calculations. The nanotube-graphene junction (NTGJ), where the GNR directly links to the CNT by covalent bonds, shows novel electronic dependence on the structural parameters of the building-blocks, such as chirality, nanotube diameter and width of the nanoribbon. For an armchair NTGJ, a small band gap opens up representing asymmetrical spin-up and spin-down bands. However, zig-zag NTGJ shows direct semi-conducting characteristics with a tunable band gap ranging from zero to 0.6 eV. Interestingly, the value of the band gap follows the specific width and diameter dependent oscillations, namely the 3p - 1 principle. Transition-state results reveal the formation of NTGJs is exothermic and has a low energy-barrier. In addition, nanotube-graphene-nanotube junctions or namely dumbbell NTGJs were also studied, which exhibits similar properties with single NTGJ.
authors.affiliation: Department of Chemistry and Shanghai Key Laboratory of Green Chemistry and Chemical Process, East China Normal University, 500 Dongchuan Road, Shanghai 200241, P.R. China. gyshi@chem.ecnu.edu.cn.
authors.forename: Zhi-bei
authors.initials: ZB
authors.lastname: Qu
authors.forename: Li
authors.initials: L
authors.lastname: Gu
authors.forename: Meina
authors.initials: M
authors.lastname: Li
authors.forename: Guoyue
authors.initials: G
authors.lastname: Shi
authors.forename: Gui-lin
authors.initials: GL
authors.lastname: Zhuang