The Synthesis And Properties Of Carbon Nanotube/nanopaticle Hybrids

Because of their unique structure and properties, carbon nanotubes (CNTs) have become an important material in the fileds of electronic, optical and biochemistry. But there are some disadvantages of CNTs which have inhibited their applications. For example, there are some metal impurities in impurified carbon nanotubes, and it is difficult to dissolve the CNTs in the water and other solvents. To solve these problems and broaden their application areas, people use various methods to modify the surface of CNTs to prepare a variety of nanocomposite materials, and study their applications. This thesis mainly studied the modification of nanoparticles on the CNT. The as-prepared materials were characterized and their nonlinear optical properties were also determined and discussed. There are four chapters in this thesis.The first chapter is a literature review, which introduce the advances and surface modification of carbon nanotubes and an overview of research idea and content of the whole thesis.In the second chapter, a layer by layer non-covalent modification method was used to modify the carbon nanotubes with metal nanoparticles. The first step is to use the surfactant cetyltrimethyl ammonium bromide (CTAB) and sodium polyacrylate (PAA) to modify the carbon nanotubes, and then the in situ growth of copper and silver nanoparticles was performed to prepare MWCNT/CTAB/PAA/M nanocomposites. The as-prepared nanocomposites were characterized by X-ray diffraction (XRD), Zeta potential, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the metal nanoparticles can be uniformly in situ loaded on the CNTs, and the mean sizes of the nanoparticles are smaller than 5 nm.The third chapter is composed of three sections: 1, synthesis of dendrimer; 2, Covalent modification was used to functionalize the carbon nanotubes with dendrimer G4.0, and then sulfide nanoparticles were in situ coated on the CNTs via the template of dendrimer G4.0; 3, The in situ growth of metal or metal oxide using CNT-G4.0 as a template. In the first part, the dendrimer with a trimesyl core was synthesized according to the literature, and then characterized by NMR. In the second part, the CNTs were covalently fucntionalized with dendrimer G4.0, then the obtained CNT-G4.0 was used as template for the in situ growth of metal sulfide (MS) nanoparticles. The resultant CNT-G4.0/MS (MS=Ag2S, CdS, CuS, PbS and ZnS) nanocomposites were characterized using XRD, Zeta potential, SEM, XPS and TEM techniques. The results show that CNT-G4.0/MS nanocomposites can be prepared successfully by using this simple method, and the mean size of the MS nanoparticles are smaller than 10 nm. The nonlinear optical properties of CNT-G4.0/MS nanocomposites were measured by open z-scanning technique. The CNT-G4.0/MS nanocomposites showed good nonlinear properties and a higher nonlinear absorption than the CNTs and CNT-G4.0. In the third part, the CNT-G4.0 was also used to in situ load Ag, Cu₂O and Ag/Cu₂O nanoparticles on CNTs. The as-synthesized nanocomposites were characterized, and their nonlinear optical properties were also studied. The results showed that, after in situ growth of Ag, Cu₂O and Ag/Cu₂O nanoparticles, nonlinear absorption of the nanocomposites was enhanced.In the fourth chapter, the important results obtained in the whole thesis are summerized. The shortcomings, improvements and the application prospects of the materials are also mentioned.