Synthesis and characterization semiconducting metal oxide nanotubes from their nanosheets

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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