Preparation and Characterization of Nonosized Photocatalytic Titania Powders and Thin Films
Date Issued
2005
Date
2005
Author(s)
Huang, Jen-Hsien
DOI
en-US
Abstract
TiO2 sol has been prepared by a novel precipitation-peptization method. Using appropriate molecule structure for chelation can enhance the rearrangement of TiO6 octahedra to form anatase TiO2. The TiO2 sol has been tested for the photocatalyzed degradation of methylene blue. The TiO2 sol shows a superior catalytic activity, which is greater than Degussa P25.
High specific surface TiO2 film coated on fibers was also prepared via dip coating method using the as-prepared TiO2 sol. The properties of TiO2 films strongly depend on the diameter of fibers. The carbon fiber with smaller diameter compared to others can load more TiO2 and this might contribute more to the heat property and photocatalytic activity. The carbon fiber also revealed better adhesion property than the other fibers and the adhesion property was promoted dramatically by the addition of binder.
Cr3+-TiO2 photocatalyst responsive to visible light was prepared by chemical coprecipitation-peptization method. Due to very low Cr content, any crystalline phase containing Cr could not be observed by XRD in Cr3+-TiO2. The DTA/TG results show that the doping chromium ions can impede the phase transformation from anatase to rutile phase. The UV-visible diffuse reflectance spectra of all the doped TiO2 samples show that the absorption shifts into visible light region. The XPS results demonstrate that the materials contain Ti, O and Cr. The intensity of chromium decreased with increasing heating temperature and it is proposed that under high annealing temperature, it can enhance the doping of Cr3+ ion into TiO2 lattice. The Cr3+-TiO2 samples revealed photocatalytic activity under visible light illumination and the photocatalytic activity was influenced by the heating temperature.
In the final part of this thesis, nanofiber TiO2 was prepared by hydrothermal method. From the XRD results, it can be assigned to trititanate H2Ti3O7 phase. The nanofibers with hydrothermal treatment showed the highest specific surface area of 327.3 m2/g. The photocatalytic activity of nanofibers was found to be better than the raw TiO2 powder.
High specific surface TiO2 film coated on fibers was also prepared via dip coating method using the as-prepared TiO2 sol. The properties of TiO2 films strongly depend on the diameter of fibers. The carbon fiber with smaller diameter compared to others can load more TiO2 and this might contribute more to the heat property and photocatalytic activity. The carbon fiber also revealed better adhesion property than the other fibers and the adhesion property was promoted dramatically by the addition of binder.
Cr3+-TiO2 photocatalyst responsive to visible light was prepared by chemical coprecipitation-peptization method. Due to very low Cr content, any crystalline phase containing Cr could not be observed by XRD in Cr3+-TiO2. The DTA/TG results show that the doping chromium ions can impede the phase transformation from anatase to rutile phase. The UV-visible diffuse reflectance spectra of all the doped TiO2 samples show that the absorption shifts into visible light region. The XPS results demonstrate that the materials contain Ti, O and Cr. The intensity of chromium decreased with increasing heating temperature and it is proposed that under high annealing temperature, it can enhance the doping of Cr3+ ion into TiO2 lattice. The Cr3+-TiO2 samples revealed photocatalytic activity under visible light illumination and the photocatalytic activity was influenced by the heating temperature.
In the final part of this thesis, nanofiber TiO2 was prepared by hydrothermal method. From the XRD results, it can be assigned to trititanate H2Ti3O7 phase. The nanofibers with hydrothermal treatment showed the highest specific surface area of 327.3 m2/g. The photocatalytic activity of nanofibers was found to be better than the raw TiO2 powder.
Subjects
光觸媒
二氧化鈦
薄膜
可見光
potocatalyst
titanium dioxide
thin film
visible light
Type
thesis
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