Amide Functionalization of Graphene and Carbon Nanotubes

Motivated by successful synthesis of dimethylamide-functionalized graphene (Collins, et al. Angew. Chem. 2011, 123, 9010), we investigate electronic, magnetic, and electron transport properties of covalently functionalized graphene and carbon nanotubes (CNTs) by the amide groups [CON(CH3)2] using density functional theory calculations. We find that when both sublattices of the graphene are evenly functionalized with the amide groups, the band gap of the modified (semiconducting) graphene can be substantially enlarged by increasing the coverage of amide groups. If the modified graphene is metallic, however, its electronic properties are little affected by increasing the coverage. When the two sublattices of the graphene are functionalized unevenly, the decorated graphene exhibits magnetism. As the coverage of amide groups is increased, the electronic properties of the functionalized graphene can be transformed from semiconducting to half metallic and to metallic. Moreover, the electronic structures of functionalized graphene can be regulated by increasing the number of zigzag chains along the supercell edge. For zigzag CNTs (ZCNTs), when the two sublattices are unevenly functionalized by the amide groups, the functionalized CNTs can be either metallic or semiconducting, depending on the pattern of decoration. ZCNTs with large diameters may exhibit magnetism as well. When the two sublattices are unevenly functionalized, the functionalized ZCNTs are always semiconducting with their band gap increasing with the distance between two neighboring amide groups in the radial direction. For armchair CNTs, however, all functionalized systems are metallic without showing magnetism, regardless of the coverage or pattern of amide groups. We also find that the conductivity of the amide functionalized graphene and CNT is lower than that of the pristine counterparts.

Amide Functionalization of Graphene and Carbon Nanotubes: Coverage- and Pattern-Dependent Electronic and Magnetic Properties

Peng Lu †‡, Rulong Zhou ‡§, Wanlin Guo *†, and Xiao Cheng Zeng *‡
† Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education and Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
‡ Department of Chemistry and Center for Materials & Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588, United States
§ School of Science and Engineering of Materials, Hefei University of Technology, Hefei, Anhui 230009, China

J. Phys. Chem. C, 2012, 116 (25), pp 13722–13730
DOI: 10.1021/jp3009578
Publication Date (Web): June 14, 2012

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