Synthesis And Characterization Of Carbon Nanotubes And Its Composite Particles

In this dissertation, we firstly develop a new kind of catalyst with great efficiency for the mass production of CNTs by CVD. Moreover, Carbon nanotube microspheres with regular shape were fabricated from acid—treated and amine functionalized carbon nanotubes(CNTs)using reverse microemulsion. In addition, the composite particles of CNTs is developed to improve the dispersibility of CNTs and to enhance the chemical compatibility between CNTs and matrix material. The research is of great significance on the theory and application potential.The Co catalysts supported on SiO2 nano-particles is prepared by chemical co-deposition. MWNTs are synthesized by Co catalytic decomposition of the mixed gas of C2H2/N2 at 740 ?. The main factors which affect the yield of carbon nanotubes(CNTs) such as temperature, time and the pH value have been researched in detail. The samples of MWNTs are purified by nitric acid and hydrofluoric acid. The morphology of crude MWNTs is observed by transmission electron microscopy(TEM). Also the samples of MWNTs which have been purified are characterized by TEM and by X-ray. The results of the experiments prove that the high quality and high yield can be produced by this method.Carbon nanotube microspheres with regular shape were fabricated from acid—treated and amine. functionalized carbon nanotubes(CNTs)using reverse microemulsion. The effects of the oil system with differentmolecular weight, the content of CNTs in ammonia water, the extent of acid treatment, and the stir temperature for emulsion on the formation and morphology of CNTs microspheres were investigated,meanwhile the mechanism of CNTs microspheres formation was studied.It is found that using CNTs acid treated for 1.5 h.CNTs microspheres with a diameter of 2—20 ?m are synthesized after vigorous sti~ing in castor oil system at85?. In addition. with increasing the contents of CNTs in ammonia water from0.27%to0.55%,the fabricated microspheres become larger,and their surfaces become more compact.Gelatin was pre-coated on the purified carbon nanotubes to introduce the functional groups on the surface. With the functionalized CNTs, cuprous oxide /carbon nanotubes(Cu2O/CNTs) superfine spheres were fabricated in situ by solution method, and the samples were characterized by scanning electron microscope(SEM)and X-ray diffraction(XRD). It is showed that carbon nanotubes were embedded in the cuprous oxide spheres with the diameter ranging from several nanometers to one micron. The reaction mechanism of the synthesis of Cu2O/CNTs composites was discussed, and it was primitively figured out that the gelatin plays a role as a bridge between CNTs and Cu2+. Cu2+ was captured by gelatin and deposited on the surface of CNTs. The effect of the dropping speed of Na OH and the ratio of mass between gelatin and CNTs on the size and the uniformity of the CU2O/CNTs composite spheres was also discussed. Finally the samples were deoxidized to Cu / CNTs composite powder.