Modification And Application Of Carbon Nanotubes

In recent years, carbon nanotubes has gradually attracted enormous interest of many scientists since it was discovered in 1991, due to unique structure and excellent properties in physical, chemical, electrical and magnetic. In addition, nanocomposites with carbon nanotubes has incomparable advantages over other materials. Therefore, the scientists hope to find some breakthroughs in the study of carbon nanotubes to synthesis of excellent performance materials. Unfortunately, the lack of solubility and the difficult manipulation in any solvents have imposed great limitations to the use of CNTs. However, CNTs can undergo chemical reactions that make them more soluble for their integration into inorganic, organic,and biological systems. In addition, it has been demonstrated that CNTs by high degree of homogeneous sidewall functionalizetion can interact with different classes of compounds.In this paper, different morphology composite nanomaterials were synthesized using as CNTs starting materials, and characterized. The main work is divided into the following several parts.Using a simple and effective way to synthesis CNTs@Fe2O3 nanocomposites, by homogeneous deposition of Fe2O3 on CNTs templates, then it was characterized by means of field-emission scanning electron microscope (FE-SEM), field-emission transmission electron microscope(FE-TEM), X-ray diffraction (XRD), Raman spectroscopy, and thermogravimetric analysis (TGA). Electrochemical performance test results show that the first discharge capacity of CNTs@Fe2O3 composite nanoparticles reach to 1139.8 mAh/g at a rate of C/10,and to 420 mAh/g after 90 cycles. The coulombic efficiency remains at nearly 97% after 3 cycles.Mesoporous carbon naotubes was synthesized by CNTs@Fe2O3 etched by HCl. The influence of experimental conditions on the size of mesoporous was studied. Under the range of C/10, the mesoporous MWCNTs deliver the first discharge capacity of 1369.4 mAh/g,which was higher than the pritine MWCNTs theory capacity and has good cycle performance,502.1 mAh/g after 14 cycles.The CNTs@Fe3O4@C coaxial nanocables, by homogeneous deposition of Fe2O3 and carbon layers in sequence on CNTs templates, exhibits higher lithium storage capacities and better cycling performance compared to CNTs@Fe2O3nanocomposites. At a rate of C/10, the coaxial nanocables maintain a reversible capacity of 810 mAh/g after 20 cycles, and 690 mAh/g after 90 cycles.