Korea National University of Transportation,
Keywords: molecular dynamics simulations, carbon nanotube, in graphene nanoribbon
Summary:Graphene, a one-atom thick layer of graphite, has recently received a lot of attention, due to its impressive mechanical and electromagnetic properties, including zero electron bandgap, high electron emission rate, and elastic scattering. Carbon nanotube (CNT), a quasi-one-dimensional nanostructure, can be thought of as graphene rolled up into a cylinder. Both CNTs and graphenes have a unique place in nanoscience, owing to their exceptional electrical, thermal, chemical, and mechanical properties; and the number of their potential applications continues to grow. As one of the engineering applications based on CNTs, gigahertz CNT oscillators were proposed by Zheng and Jiang, after Cumings and Zettl reported an ideal low-friction and low-wear bearing carved out of a multi-walled CNT with a diameter of a few tens of nanometers, and they have been intensively investigated. Moreover, graphene oscillators based on the interlayer sliding of graphene nanoribbons (GNRs) or graphene nanoflakes (GNFs) have been addressed. Recently, conjugated carbon nanomaterials, such as fullerene-nanotube, fullerene-graphene, and nanotube-graphene hybrids, also have great potential application. Fullerene-nanotube hybrids termed carbon nanopeapods have been widely investigated. Quite recently, fullerene-graphene hybrids have been experimentally produced and theoretically investigated. In particular, nanotube-graphene hybrid also has great potential application. Theoretical work suggested that a covalently bonded graphene-nanotube hybrid material would extend those properties to three dimensions, and be useful in energy storage and nanoelectronic technologies. Zhu et al. disclosed a method of seamlessly bonding graphene and single-walled CNTs, during the growth stage. The hybrid material exhibited a surface area > 2,000 m2 g−1, with ohmic contact from the vertically aligned single-walled CNTs to the graphene. Using aberration-corrected scanning transmission electron microscopy, they observed the covalent transformation of sp2 carbon between the planar graphene and the single-walled CNTs, at the atomic resolution level. Their findings provided a new benchmark for understanding three-dimensional graphene-nanotube-conjoined materials. In our previous work, using CNT-GNR hybrid, we proposed nonvolatile CNT-shuttle-memory on GNR array, and investigated its dynamics via classical molecular dynamics (MD) simulations. In this work, we present CNT-oscillator encapsulated in GNR trench as a CNT-GNR hybrid, and its operational properties, using atomistic simulations. Since the energy barrier while the CNT was encapsulated in the GNR trench was very low at 2.08 meV/atom, the CNT absorbed on the GNR surface could easily be encapsulated in the GNR trench. The motions of the CNT in the GNR trench were similar to those of the core CNT encapsulated in an outer CNT, and as a result, the CNT in a GNR trench can work as an oscillator. The results obtained from the MD simulations in this work showed that the CNT oscillator encapsulated in a GNR trench is compatible with simple CNT oscillators.