Synthesis And Application Study Of One-Dimensional Carbon Nanomaterials

Since the discovery of carbon nanotubes (CNTs) by Iijima in 1991, carbon nanotubes have attracted much attention due to their scientific significance and potential technological applications. The synthesis, properties and applications of CNTs have become a hot research field. Developing new preparation methods and new systems of carbon nanotubes are very important research programs in the fields of physics, chemistry and materials science.In this thesis, we synthesized various of carbon nanomaterials by thermal Chemical Vapor Deposition (CVD) method, such as carbon nanofibers, bamboo shaped carbon nanotubes, multiporous carbon nanofibers, single walled carbon nanotubes, double walled carbon nanotubes, multi walled carbon nanotubes and so on. We mainly used two kinds of catalysts, one is alkali doped Cu/MgO catalysts fabricated by sol-gel combustion method; the other is Fe doped Mo/Mg catalysts fabricated by sol-gel combustion method and freeze-drying method. TEM, SEM, HRTEM, Raman, XRD, EDS, TGA and some other characterization methods have been used to characterize the carbon nanotubes and carbon nanofibers, and their electrochemical behaviors have been estimated by the battery instrument and the electrochemical workstation.When we used acetylene as the carbon-contained gas, hydronitrogen and hydrogen as carrier gases, NH3 as the doped gas, carbon nanomaterials with various microstructures were obtained by CVD method. The final products included CNTs, bamboo-shaped CNTs, multi-branched porous CNFs and so on. The catalysts wouldn't have any catalytical property without alkali doped. We can easily control of carbon nanostructure by adjusting the process parameters, such as the alkali content, reaction gas, reaction temperature and reaction time. The carbon nanofibers show fascinating potential in the electrochemical double-layed capacitors due to their porous structure.Carbon nanotubes with different walls number were synthesized on Fe doped Mo/MgO catalysts using CH₄ as carbon-contained gas, H₂ as the carrier gas by CVD method. We found that the catalysts fabricated by freeze-drying method were more beneficial than the catalysts fabricated by sol-gel combustion method to control the walls number of carbon nanatubes. Both the walls number and the yield of final products were increasing with the increasing of Mo content.