| Summary: | 碩士 === 國立東華大學 === 材料科學與工程學系 === 93 === This study focuses on the preparation, structure, composition, properties and the visible light photocatalytic activity of carbon doped titania (TiO2-xCx) films. The TiO2-xCx films were prepared by ion-assisted electron-beam evaporation using rutile TiO2 powder as source material.
XRD, Raman and XPS were used to detect the films structure, component and surface composition. SEM and surface profiler were used to observe the surface morphology and to measure the film roughness. The photocatalytic and hydrophilic properties of the films were characterized by the water-contact angle measurement and the degradation of methylene-blue (MB) solution, respectively. The visible light source is a fluorescent lamp with the wavelength distribution around 400~700 nm and the power density on the sample surface is 1.51 mW/cm2.
The results show that the structure of the deposited TiO2-xCx films was anatase characterized by XRD and Raman spectra. With the raising ion beam current, the ion bombardment became more intensive, resulting rising carbon content in the TiO2-xCx films and red-shift in absorption edge. As the ion beam current was raised over optimal level, the anatase crystallinity of the films determinated, with the appearance of rutile phase.
Two different gases of CO2 and CO were utilized in the ion source to prepare the TiO2-xCx films. More carbon content has been incorporated when CO2 gas was utilized as the ion source and caused the film absorbance edge shifted to the higher wavelength region. The film deposited at 10 mA beam current from CO2 source exhibited the lowest contact-angle of 3° and the best photocatalytic activity in the reduction of silver ions to metal and in the degradation of methylene-blue with a rate-constant (k) about 0.108 hr-1 under visible-light illumination.
After annealing at 500oC, the crystallinity of the anatase TiO2-xCx films improved, but their absorption edges blue-shifted a little. After annealing, the film contain 1.3 at% carbon have the best degradation of methylene-blue rate-constant about 0.170 hr-1 which was 1.5 times higher than before annealing. This study demonstrates that the anatase crystallinity of the titania based films is the dominant factor for their photocatalytic performance.
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