Preparation Of Large-diameter CNTs And Carbon Encapsulated Metal Nanoparticles

CNTs have excellent electrical,mechanical properties and thermal performance, that have become an urgently demanded to versatile applications in high power electronic devices, electric vehicles, strengthen material and heat dissipation material. At present, CNTs have attracted intense interests as electrode materials for supercapacitors, because of their tubular structure can be filled with guest molecules and serve as microchannels for ion or molecular transport. Large-diameter and porous CNTs can act as catalyst support and electrode materials because its large diameter and porous structure. At present, the main industrial growth of CNTs is chemical vapor deposition(CVD) method, however, CVD CNTs have very disordered structures and a high content of defects including vacancies, dangling bonds, edges and dislocations, these have seriously restricted their excellent performance. In addition, carbon encapsulated magnetic nanomaterials have received considerable attention because of their unique core/shell microstructure and physical chemical properties, The carbon encapsulated can immunize the nanoparticles against environmental degradation and therefore retain their intrinsic nanocrystalline properties, moreover, carbon encapsulation can endow these magnetic nanoparticles with better electrical conductivity and higher biocompatibility. Based on the above two points, our main work is synthesize Large-diameter and porous CNTs(LPCNT) by using Ni nanowire templates and using a simple method to synthesize carbon-encapsulated Cobalt-nickel nanorods and Cobalt nanoballs. The main work of the thesis is as follows:(1) We use a effective carburization process with low temperature to bring the carbon atom into Ni nanowire templates, then they were annealed in high temperature, in this process,the carbon atom transfer to the surface of nickel nanowires, with the time increase, the carbon sheet formed on the surface, the productions are immersed into HCL solution to dissolve the Ni-nanowires, then the Large-diameter and porous CNTs are formed. The morphology and structure of CNTs are examined by TEM and XRD characterization. The diameter of this CNTs is mainly concentrated in 400-600 nm,the capacitance of the Large-diameter and porous CNTs is 74.F/g(2) First, Cobalt-nickel nanorods are synthesized, and the role of ruthenium is to seed the growth of cobalt and nickel. We have researched the affect of Cobalt-nickel nanorods for different Co/Ni molar ratio. The Cobalt-nickel nanorods with a mean length of about 35nm-50 nm, the diameter of Cobalt-nickel nanorods is about 8nm on its both ends, and the middle section width is about 4nm, and we also use a simple method to completed its carbon-encapsulated process. The room-temperature magnetic properties of the carbon-encapsulated Cobal-nickel nanorods were measured before and after the thermal treatment at 400℃,the saturation magnetization is 60.1 emu.g-1(3) we use to synthesize Co-nanoballs, and its carbon-encapsulated process were also completed. We could control the reaction time to control the thickness of carbon sheet. The crystallinity of the carbon sheet were characterized by transmission electron microscopy and Raman spectroscopy, and the saturation magnetization and coercivity of carbon-encapsulated Co-nanoballs were measured.