Preparation And Photocatalytic Property Of TiO₂-、Zno- And ZrO₂-based Structured Nanofiber Materials

In this thesis, a series of different metal ions-dopped (Zn2+, Ti4+, Zr4+) TiO2-and ZnO-and ZrO2-based structural nanofiber materials (Zn2+/Ti02, Ti4+/ZnO, Zr4+/ZnO and Zr4+/ZnO) and metal ions (Zr4+, Zn2+) versus-dopped ZnO- and ZrO- based semiconductor-coupled nanofiber materials (Zn2+/ZrO2-Zr4+/ZnO and Zr4+/Zn0-Zn2+/ZrO2) were prepared via dipping-calcination two-steps method (TSM) by using cotton fibers (CF) as the template and characterized by thermogravimetric analysis (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence spectra (PL) techniques. Their photocatalytic properties were evaluated by using the degradation of dye methylene blue (MB) solution as model reaction. This thesis mainly consists of following two major aspects.1. A series of different metal ions-dopped (Zn2+, Ti4+, Zr4+) TiO2- and ZnO- and ZrO2-based structural nanofiber materials, Zn2+/TiO2, Ti4+/ZnO, Zr4+/ZnO and Zr4+/ZnO were prepared via TSM by using CF as the template and characterized by TG, XRD, SEM, TEM and PL techniques. The effect of Zn2+, Ti4+, Zr4+-dopped amount on their photocatalytic properties were investigated by the degradation of MB solution on their surface. The mainly results are described as follows:a. The series of different metal ions-dopped (Zn2+, Ti4+, Zr4+) and structured nanofiber materials with hollow structure, Zn2+/TiO2, Ti4+/ZnO, Zr4+/ZnO, and Zn2+/ZrO2 were prepared via template-assisted TSM and these materials are assembled by nanopaticles (<24nm). Respectively introducing Zn2+ and Ti4+ into TiO2 and ZnO can make the linkage of inter-nanoparticles better in the Zn2+/TiO2 and Ti4+/ZnO materials. And ZnO-based materials show the morphology of multi-walls structure.b. Introducing Zn2+ions into TiO2 bring about the conversion of anatase-TiO2 to rutile-TiO2. It is that there is the junction of anatase-rutile in the sample Zn2+/Ti02. Dopping Ti4+, Zr4+ and Zn2+ ions does not result the phase change of ZnO and ZrO2.c. In the range of dopped Zn2+(0～0.30 at.%) and Ti4+(0～0.200 at.%), the photocatalytic property of Zn2+/TiO2 and Ti4+/ZnO nanofiber structured materials is higher than pure TiO2’ and ZnO’ while a proper amount of dopped Zr4+ and Zn2+can increase the photocatalytic activity of ZnO and ZrO2, respectively. The degradation of MB molecules follow first-order dynamics behavior ln(C0/Ct)=kit. Many factors affect the performance of the semiconductor catalysts, such as composition, structure, size, surface state, morphology, and so on. The improved photocatalytic property of Zn2+/Ti02 and Ti4+/ZnO can be ascribed to nanosize (about 22～24 nm), anatase-rutile junction, structure defect, special morphology (from the assemble of nanoparticles), especially multi-walls morphology.2. A series of Ti4+and Zn2+ ions versus-dopped TiO2- and ZrO2- based semiconductor-coupled structural nanofiber materials, Zn2+/ZrO2-Zr4+/ZnO and Zr4+/Zn0-Zn2+/Zr02, were prepared via TSM by using CF as the template and characterized by TG, XRD, SEM, and TEM techniques. The effect of semiconductor-coupled amount on their photocatalytic properties were investigated by the degradation of MB solution on their surface. The results show that there are metal ions versus-dopping in the semiconductor-coupled materials Zn2+/ZrO2-Zr4+/ZnO and Zr4+/ZnO-Zn2+/ZrO2 and in the range of coupled amount (ZrO2:0～2.5 at.%, ZnO:0～15 at.%), the samples Zn2+/ZrO2-Zr4+/ZnO and Zr4+/Zn0-Zn2+/ZrO2 show better photocatalytic property than pure ZnO and ZrO2, respectively. The improved photocatalytic property of Zn2+/ZrO2-Zr4+/ZnO and Zr4+/Zn0-Zn2+/Zr02 can be ascribed to ZrO2-ZnO junction and the defect of their phase structure, resulted from versus-dopped metal ions.