Research Progress on the Preparation and Application of Carbon Nanotubes

Carbon nanotubes (CNTs) are tubular structures composed of highly graphitized atoms. Due to the sp2 hybrid electron orbital structure, CNTs possess a variety of unique physical and chemical properties, such as high mechanical strength, excellent optical anisotropy and good electrical conductivity. Therefore, CNTs are promising advanced materials that can be used in areas of material strengthening, energy conversion and electronic devices. The structures and properties of CNTs can be tuned by regulating the growth environment of CNTs. Nevertheless, the growing process of CNTs is very complicated, and highly depended on raw material, preparation method and growth environment, which consequently determine the growth rate, microscopic morphologies and final properties of CNTs. In the present paper, the effects of fabrication methods, substrates, catalysts, and growth environment on the microscopic morphologies and properties of CNTs were reviewed, and the growth mechanisms of CNTs are discussed. We also pay attention to the application of CNTs in the areas of energy storage, material toughening and catalytic hydrogen production. The present deficiencies and future development directions on the preparation and controlled growth of CNTs are figured out, which provides guidance for the controlled growth and large-scale preparation of CNTs.