Preparation Of Ceria Hollow Tubes And ZnO/Ag Composites

Ceria was widely used in Automobile exhaust, water treatment, solid-state oxide fuel cells,biosensor, and polishing powder. And now, owing to its special performance, cerium oxide tubehas been the research focus in relative field. In this dissertation, cerium oxide tube wassynthesized using fibers as templates; a thin CeO2layer first was coated around the fiber byvapor deposition. Then ceria hollow tubes were obtained after sintered at600℃for two hours.Using same technology, CeO2/Au tubes were also synthesized by gold plating on the fiberssurface. In addition, a simple one-pot hydrothermal method was used to prepare ZnO/Agcomposites by adding zinc acetate and silver nitrate in into a high temperature glycol solvent.The main contents and results are described as follows:1. Ceria hollow tubes were synthesized by template method and vapor deposition. Thefibers as templates were coated with a thin CeO2layer by vapor deposition. The fiber compositesthen were sintered in muffle furnace, which results in forming of ceria hollow tubes. In thisdissertation, the hollow tubes will be optimized in the following aspects.First, considering the effects by using different templates, in this dissertation, cerium oxidehollow tubes were prepared with fibers as templates, such as polyester fibers, cotton fibers,acrylic fibers and wool fibers. The fibers composites were successfully synthesized by thesefibers as templates. The wool fibers were covered completely and a smooth surface without anywool scales through the observation.Second, considering the effects by using different surfactants, in this dissertation, ceriumoxide hollow tubes were prepared by using different surfactants, such as PVP and PEG. The fibercomposites then were sintered in muffle furnace, which results in forming of ceria hollow tubes.The ceria hollow tubes have been synthesized completed with a smooth surface.Last, to ensure the mass ratio between cerium nitrate and PEG, in this dissertation, ceriumoxide hollow tubes were prepared by using the different mass radio, such as1:1,1:2and2:1,cerium oxide hollow tubes were prepared with wool fibers as templates. The wool fibers firstlywere coated with a thin CeO2layer by vapor deposition. The fiber composites then were sintered in the muffle furnace, which results in forming of ceria hollow fiber. The ceria hollow tubes havebeen perfectly synthesized completed with the diameter size of8~12μm and a smooth surfaceby choosing the mass radio of1:1.2. On the foundation of the successful preparation of ceria hollow tubes. Here, we firstcoated Au layer on wool fibers. Then we used the wool fibers/Au as templates, the woolfibers/Au were coated with a thin CeO2layer by vapor deposition. The fiber composites thenwere sintered in muffle furnace, which results in forming of CeO2/Au hollow tubes with thediameter size of8~12μm and smooth surface.3. In this dissertation, a simple one-pot hydrothermal method was used to prepare ZnO/Agcomposites by adding zinc acetate and silver nitrate in turn into a high temperature glycol solvent.First, the ZnO particles were synthesized in a hydrothermal method. Then the AgNO3solutionand the PVP solution were synchronously dropped into the flask with a rate of0.3ml/min. Thesolution was kept at160℃, then the suspension was cooled to room temperature and theprecipitates were separated and washed with acetone. During synthesis, the octahedral ZnOparticles with sizes ranging from1to3μm, and the spherical silver nanoparticles with adiameter of about20nm were uniformly distributed on the surface of the ZnO particles.