Synthesis and characterization semiconducting metal oxide nanotubes from their nanosheets

近年来，包括纳米管和纳米纤维在内的一维纳米材料受到了人们的广泛关注。这些材料表现出一维量子效应对其电子、磁性和光学性质的影响。到目前为止，一维纳米材料的制备面临着许多挑战，包括气相法制备、液态法制备、固相法制备。这些过程大多属于自下而上的过程。它们在一维方向上控制晶体生长方向，或使用具有一维形貌的模板。在本研究中，我们开发了一种从金属氧化物和金属氢氧化物纳米片制备纳米管的新工艺。该过程属于一种新的利用软化学反应的纳米尺度的自上而下的过程。利用主/客体反应的软化学反应是一种独特而实用的方法。它可用于纳米结构的修饰和纳米材料的制备。在合成氧化锰纳米管和纳米纤维时，首先是H‘形的水钠锰矿-…采用四甲基氢氧化铵溶液在室温下对具有层状结构的多种类型的锰氧化物进行处理，使水钠锰矿剥离成氧化锰纳米片。在纳米片状胶体溶液中加入阳离子表面活性剂(N-十烷基三甲基氯化铵，DETA-C1)溶液，制得氧化锰-DETA‘纳米复合材料。纳米复合材料在水热条件下进行处理，将纳米片转化为纳米管和纳米纤维。用这种方法制备的锰氧化物纳米管和纳米纤维具有半导体性质，禁带能为0.43 eV。为了制备金属氢氧化物纳米管，我们首先用水热反应制备了一系列层状的碱性金属盐--苯甲酸锌和苯甲酸镍。将层状碱性金属盐在乙醇溶液中剥离，得到层状氢氧化锌和氢氧化镍纳米片。这些层状金属氢氧化物纳米片可以通过干法卷曲成纳米管。较少

Recently, much attention is focused on 1D nanomaterials, including nanotubes and nanofibers. These materials show 1D quantum effects on their electronic, magnetic, and optical properties. Up to now, many challenges have been carried out on the preparation of the 1D nanomaterials, including use of vapor process, liquid process, and solid process. Most of these processes belong to the bottom-up process. They control the crystal growth direction in 1D, or use of templates with 1D morphology.In the present study, we have developed a novel process for the preparation of the nanotubes of metal oxides and metal hydroxide from their nanosheets. This process belongs to a new top-down process in nanoscale using soft chemical reactions. The soft chemical process using host/guest reactions is a unique and useful method. It can be used for modification of nanostructures and fabrication of the nanomaterials.In the synthesis of manganese oxide nanotubes and nanofibers, first an H'-form of birnessite- … More type manganese oxide with layered structure was treated in a tetramethylammonium hydroxide solution at room temperature to exfoliate the birnessite to manganese oxide nanosheets. A cationic surfactant (n-decyltrimethylammonium chloride (DeTA-C1)) solution was added into the nanosheet colloidal solution, and then a nanocomposite of manganese oxide-DeTA' was obtained. The nanocomposite was treated under hydrothermal conditions to transform the nanosheets into the nanotubes and nanofibers. The manganes oxide nanotubes and nanofibers prepared by this method showed semiconducting properties with band-gap energy of 0.43 eV.To prepare of metal hydroxide nanotubes, first we prepared a series of layered basic metal salts of zinc hydroxide benzoate and nickel hydroxide benzoate using hydrothermal reactions. The layered basic metal salts were exfoliated in alcohol solutions to obtain the nanosheets of the layered zinc hydroxide and nickel hydroxide. These layered metal hydroxide nanosheets can be curled into nanotubes using a dry process. Less