Preparation And Characterization Of Low Dimensional Semiconductor Nanomaterials (VIa Group)

In recent years, low dimensional materials have been a research focus for that they can be easily assembled into plenty of special functional materials. A lot of novel low dimensional nanomaterials such as nanorods, nanotubes, nanowires, nanobelts, nanofilms and nano coaxial-cable have been prepared with the development of nanotechnology. Meanwhile, the successfully measurement and application of the single nanostructure have further improved the control synthesis of the low dimensional nanomaterials as well as the exploration of the formational mechanism.VIa group compounds (CdSe, ZnSe and CdS) or simple substance of the element (Te and Se) are both the important semiconductor materials which can be used extensively in the fields of nonlinear optics, photoelectric conversion, photoabsorption and photocatalysis. Hydrothermal method, which is known as a solution-based chemical method, may be an effective and convenient approach to prepare the VIa group nanomaterials with great advantages such as high efficiency, inexpensive equipments, and dispensing with any inert atmosphere protections. It has been developed and widely used in preparing 1D nanomaterials. It is also one of the most promising methods for controlling product morphology, size, and size distribution in nanomaterials fabrication.In this paper, we prepared a series of VIa group compounds and simple substance nanomaterals using the hydrothermal method and their morphologies, structures, and properties were characterized by TEM, HRTEM, SEM, XPS, EDX, UV-Vis and PL, respectively.Single crystal Se nanosheets and nanowires were prepared through ethylenediamine assistant hydrothermal method and CVD method respectively. It carried out the conversion of Se from the powders of the stock materials to the single crystal sheet-like structures, whose SSS (solid-solution-solid) process may be different from the previous process of VS ( Vapor-Solid ) or VLS (Vapor-Liquid-Solid) . Moreover, the 1D channel like single crystal Te was also prepared by the ethylenediamine assistant hydrothermal method. The results show that the 1D Te has the hexagonal crystal phase and grows along the [001] directions.The CdSe nanorods, which have high crystallinity and grow along a certain crystal directions, were fabricated through the hydrothermal process. The formation mechanism of the nanorods was interpreted by an intermediate complex Structure-controlling mechanism.Quantum dots (such as CdSe and CdS semiconductor nano crystals), which have the quantum confinement effect, size-dependent optoelectronic properties and the strong anti blanch properties, have been very attractive materials in optoelectronics and biosensors. In the chemical modification of the carbon nanotubes the research of the CNTs-QD heterojunctions attracted more interest of researchers. In this paper we carried out the in situ .growth of the CdSe and CdSe/CdS quantum dots on the MWCNTs in a innocuous solution and at a lower temperature using the thioglycollicacid as the stabilizer. The results show that the particles of the quantum dots are uniform and the CdSe -CNTs #3 CdSe/CdS-CNTs heterojunctions have a distinct PL phenomena.TiC>2 can be used as electrode materials in the lithium ion battery. In this section we prepared the TiC>2 nanotubes by fluxing and hydrothermal process and studied the possibility of these materials used as the cathode electrode materials. The results show that the TiO2 nanotube electrodes have a higher reversible capacity and better stability than the TiC>2 raw materials. In addition, we also carried out the preparation of the Pt/TiO2 nanotube composite materials using a microwave assistant polyalcohol reduction method. These materials show the electrocatalytic activity for the electrooxidation of methanol when used as the catalyst in the methanol fuel cell.As a wide-gap semiconductor, the preparation of ZnO nanorods has attracted great interests. In this section, we carried out assembling ZnO nanorods into chrysanthemum-like crystals by the assistance of SDS (dodecyl sodium sulfonate). The results show that the chrysanthemum-like crystals were composed by plenty of lanciform ID ZnO nanorods which grow along [0001] dirction with about 200nm in diameters and 1 um in length.