MD Simulation Of The Graphene Core/Shell Nanocomposites

In 2004, Geim, et al. discovered the quasi-two dimentional carbon material by a very simple method, which is called'graphene'(GN). Because of the unique structure, GN has series of perfect properties, inclusing quantum tunnel effect, half integral quatum Hall effect, never disappeared conductivity, and so on. And this promising material has attracted tremendous interests among the scientific domain. Since the GN has been discovered, there have been many reports about the GN research, and the pace of development is so rapid that it has almost caught up with the developing pace of carbon nanotube's (CNT's). Due to the nanosize of CNTs and GNs, it is very difficult to measure their's properties. So using molecular simulation method has much more advantages. The main purpose of this article is to research the interaction between CNT and GN, and the interaction between nanowire (NW) and GN, and to describe the self-scrolling process of forming CNT/CNS, NW/CNS core/shell composite nanostructures, and to explain the mechanism of this self-scrolling process.First, MD simulation based on the COMPASS force-field has supplied a simple method to investigate the GNs self-srolling onto CNTs to form the novel CNT/CNS core/shell composite nanostructures. And the GNs self-scrolling process affected by GN's length, chirality, et al. has also been investigated. It is found that CNT's radius has a critical effect on forming the CNT/CNS core/shell composite nanostructures. Only the CNTs with the enough large radius (about 10 ?) can activate the GN's self-scrolling onto CNTs to form the the CNT/CNS core/shell composite nanostructures, because of their large van der Waals force. Our simulations futher indicate that the interaction energies between the CNTs and GNs increase with the increasing GNs'length. And the formed CNS produced by self-scrolling long GN onto CNT is much more like the multi-walled CNT. In this paper, we can control the CNS's diameter and chirality by modulating the CNT's diameter and the GN's chirality in a determinate way. Although the chiralities of both CNT and GN have no strong influence on the self-srcolling process, which thus enables the fabrication of a core/shell structure that combines metal/semiconductor, metal/metal, or semiconductor/semiconductor junctions.Furthermore, we report that the NWs can also activate the GN's self-scrolling to form the NW/GN core/shell composite NWs. In this paper, we choosed eight nanowires, inclusing seven metal nanowires (Ni, Pd, Au, Pt, Cu, Ag, Al) and one semiconductor nanowire (Si), to interact with the GNs. The simulations show that there is also a threshold value of the NWs'radius which can activate the self-scrolling process of GNs. As for Ni, Pd, Au, Pt, Si NWs, the threshold radius value are 5 A, for Cu and Ag are 6 A and for Al is 7 A. The interaction energies between the NWs and GNs also increase with the increasing GNs'length, and the weakest interaction energy among the eight NWs and the GNs is the interaction energy between the Si NW and the GN, which lead to the largest layer space between the Si NW and the formed CNS. The GN's width has little influence on the interaction between NWs and GNs. Depending on different GNs and different species of NWs, the NW/GN architectures produced various heterogeneous core/shell nanostructures, which may bring a wide rang of potential applications, such as corrosion filed, photoelectricity apparatus, integrated circuits and transmission cable.Our simulation data and results, which could reduce the research period and the cost, would be of great importance in the fabrication of novel core/shell composites. The results also provide the possibility of using these novel core/shell composites to fabricate supercontainer, nanodiode, hydrogen storage, photoelectricity device, nanoactuator, etc.