Special Morphology One-Dimensional Semiconductor Nanomaterials Synthesis And Mechanism Research

In addition to the ordinary one-dimensional nanomaterials nanowires, nanorods, nanobelts, nanotube,complex shape one-dimensional nanostructures or that formed by assembling the simple one-dimensional nanomaterials has became one of the frontiers and hot spots in physical, chemical, materials and other areas because of its peculiar properties, and other potential applications in many fields, such as future (optical) electronic nano-devices, chemical catalysis, electrochemistry, nano-mechanical.The preparation of special morphology one dimensional nanomaterials, such as coaxial cable, nanomaterials heterostructure (for example, nanowires and nanowires, nanotubes and nanowires, nanotubes and nano-tubes, etc.), has drawn increasing attention because of its potential applications. In this paper, we synthesized the "zigzag SnO2nanowires","CdS nanowire/carbon nanotube heterojunction arrays"," aluminum zinc nanotube arrays"," ZNAL2O4/ZnO composite nanotube arrays "," multi-channel ZNAL2O4nanotubes" and "ZnO/ZnAl2O4composite nanotubes and carbon nanotubes heteroj unction" by combineing the methods of chemical vapor deposition, the template method, solid-state reactions, chemical etching and other methods.The main content and innovation of this research are as follows:1. Synthesized the "Zinc aluminum nanotube arrays","aluminum zinc/zinc oxide composite nanotube arrays" and "zinc oxide/zinc aluminum composite nanotubes and carbon nanotube heterojunction arrays".Synthesize Zinc nanowires through electro-deposition route in AAO template. Zinc nanowires were annealed at300℃～350℃for40hours, then annealing at high temperature (680℃～700℃) for1hour. At last,"zinc aluminum nanotube arrays" and "aluminum zinc/zinc oxide composite nanotube arrays" were obtained by NaOH etching treatment. Through analysis the preparation mechanism of aluminum zinc nanotubes, we identify the main reason to form tube is because of the diffusion and reaction between zinc oxide and aluminum oxide at the interface (Kirkendall effect). We also determined the main factors affecting the preparation process are alumina template size, high-temperature annealing time and NaOH etching conditions, etc.."Aluminum zinc nanotube arrays" and "aluminum zinc/zinc oxide composite nanotube arrays" controlled preparation were realized by controlling these factors. Based on the zinc oxide nanowires, we adopt the chemical vapor deposition to assemble carbon nanotubes, and obtained "zinc oxide/zinc aluminum composite nanotubes and carbon nanotube heteroj unction arrays". In heterojunction, the "zinc oxide/zinc aluminum composite nanotubes" outside diameter is124～45nm, inside diameter is63-67nm, carbon nanotubes outside diameter is81nm, inside diameter is about70nm.2. Synthesized a large number of the same morphology and special structure of "multi-channel aluminum zinc nanotubes" at the first time.The internal structure was composed of eight parallel small nanochannels; outside diameter is about450nm and its outer surface was composed of multiple semi-circular cylinder which parallel to each other, length up to20microns at visible range. The preparation of "Multi-channel aluminum zinc nanotubes" contain the following conditions:zinc nanowires annealed at low temperature of300℃-350℃for40h and high temperature of680℃-710℃for15h, finally, selective etching process using NaOH solution. Through forming mechanism analysis, this paper argues that prepared by "multi-channel aluminum zinc nanotubes" mainly due to the selective etching of NaOH solution, that is aluminum zinc grain boundaries and subgrain boundaries energy is high, preferentially etched by NaOH solution. As the "multi-channel aluminum zinc nanotubes" has a high specific surface area and special morphology, there are potential applications in chemical catalysis, luminescence, etc..3. Synthesized the "CdS nanowire/carbon nanotube heterojunction arrays" and "carbon nanotube/CdS nanowire/carbon nanotube heterojunction arrays"."CdS nanowires/carbon nanotubes heterojunction array " and " carbon nanotubes/CdS nanowires/carbon nanotubes heterojunction arrays" were synthesized by chemical vapor deposition method, which was based on the prepared alumina template and CdS nanowires. Detection showed that the CdS nanowires in the heterojunction is single crystal structure. The carbon nanotubes are layer structure. CdS, which has significant photoelectric effection, is the most valuable material in the application of Ⅱ-Ⅵ clan compound semiconductor. Carbon nanotubes have unique electrical, optical, and mechanical properties. The heterojunction arrays, assembled by the two kinds of materials, will have an important potential applications in optoelectronic nano-devices, etc. 4. Synthesize the single crystal zigzag SnO2nanowires and studying their optical properties.Zigzag SnO2nanowires with the single crystal structure have been synthesized by chemical vapor deposition, using the metallic Sn powder as the raw material. The sawtooth type nanostructure in [101] and [101] direction growth periodically. The serrated side length is almost the same, on the same nanowire and its width remains unchanged. The sawtooth cycle length varies between2μm～6μm. The nanowires' length is up to120microns at visible range. Zigzag SnO2nanowires have three strong emission peaks at room temperature at373nm,421nm and477nm wavelength.In this paper, we combined the different preparation methods of nano-materials to synthesize several special morphology complex quasi one-dimensional nanomaterials, which provides a new way for the preparation of complex morphology nano-materials. That laid the foundation for explore the special properties of nanomaterials.