Graphenylene-based nanotubes |
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| Andrew T. Koch, Saloome Motavas, Harrison D. E. Fan, Amir H. Khoshaman, George Sawatzky, Alireza Nojeh |
| Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia, Canada |
| Physics, University of British Columbia, Vancouver, British Columbia, Canada |
| Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia, Canada |
| akoch@ece.ubc.ca |
| The electronic properties of a new type of carbon nanotube based on the graphenylene motif were investigated using density functional and tight-binding methods. The structure of a graphenylene nanotube consists of six-membered as well as four-membered rings of sp2 carbon atoms, with localized pi bonds fixed around the six-membered rings. As a result, these nanotubes exhibit three distinct bond lengths between carbon atoms. They also possess unique dodecagonal pores with ~5.4 Å diameter. Analogous to conventional graphene-based carbon nanotubes, a two-dimensional graphenylene sheet can be “rolled” into a seamless cylinder in armchair, zigzag, or chiral orientations. The resulting nanotube can be described using the familiar (n,m) nomenclature. Density functional theory-based calculations predict zigzag graphenylene nanotubes to be small bandgap semiconductors, with an increasing bandgap as the diameter decreases. Similar to traditional carbon nanotubes, zigzag graphenylene nanotubes with indices mod(n-m,3)=0 exhibit a smaller bandgap than other zigzag graphenylene nanotubes with comparable diameters. Interestingly, density functional calculations predict metallic behavior for armchair graphenylene nanotubes with small diameters (< 13 Å), and semiconducting behavior with a small bandgap for armchair graphenylene nanotubes with larger diameters. References: [1] J. M. Soler et al. J. Phys.: Condens. Matter 14 2745 (2002) [2] D. Porezag, T. Frauenheim, T. K. Kohler, G. Seifert, R. Kaschner, Phys. Rev. B 51, 12947−12957 (1995) [3] G. Brunetto et al. J. Phys. Chem. C, 116, 12810-12813 (2012) [4] Q. Song et al. J. Mater. Chem. C, 1, 38 (2013) |