Studies On The Preparation And Modification Of Multi-walled Carbon Nanotubes

Since carbon nanotubes (CNTs) have been discovered in 1991, they have become to be a focus of attention in nano-technology for their unique characters and special tube structure made of graphite flakes. There are some preparation methods, such as arc discharge method, catalytic chemical vapor deposition technique, plasma sputter method, polymer pyrogenation technology etc. With the progress of synthesis technics and purification methods of CNTs, the synthesis and superficial modification of CNTs are new aspects of research.Stable frame and chemical inactivity belong to the CNTs. No matter what a modification method we adopt, the effect of modification depends on the kinds and the amount of the chemical groups on the wall of CNTs. Thus it is important to research superficial management technics to produce and increase exterior chemical groups. Dense nitric acid is usually used to produce chemical groups on the wall of CNTs. Oxidation of nitric acid on the CNTs results in the open of the end and the wall of the CNTs, and induces chemical groups to CNTs. Then we can decorate CNTs on the chemical groups.Development of nano-materials and their physical traits are briefly recited. In particular, CNTs'structure, preparation, growth mechanism and application are elaborately expounded. In this paper, we discuss the preparation and modification of CNTs. The most contents of the thesis are as follows:1. High-quality multi-walled carbon nanotubes (MCNTs) were prepared by CVD decomposing ethylene, using iron catalyst supported on alumina. The keys of the preparation are also discussed.2. MCNTs were prepared using cobalt catalyst supported on multi-walled carbon nanotubes. The new method resolves the problem at the certain degree, that there is some unremovable oxide supporter in the products.3. Grain and silk forms of MnO2 coating on multi-walled carbon nanotubes were prepared by controlling reaction conditions of KMnO4 and MCNTs/HNO3.Possible growth mechanisms of the MnO2 were proposed.4. Using CNTs containing some hydroxide groups as carrier, different forms of ZnO coating on multi-walled carbon nanotubes were prepared by two methods. The product, pure CNTs and pure ZnO degraded methyl orange separately, and the product had the best effect.