Key Words:SiO2/TiO2 Films; Sol-Gel; Al2O3 Films; Photocatalytic Activity; Phase Transformation
Abstract:SiO2/TiO2 sols were prepared via a novel sol-gel process using TiCl4 and industrial SiO2 sol as starting material precursors. A series of SiO2/TiO2 composite films were formed via a dip-coating route on ceramic substrates precoated with 4 layers of Al2O3 films, and characterized using an X-ray diffractometer (XRD), a field-emission scanning electron microscope (FE-SEM) and a Fourier transform infrared (FT-IR) spectrometer. The effect of SiO2 on the anatase-rutile phase transformation in the films was also examined. The results showed that the presence of SiO2 greatly retarded the anatase-rutile transformation and inhibited the grain growth of TiO2. The anatase-rutile transformation temperature increased from 700 degrees C (in the case of pure TiO2 to 1000 degrees C (in the case of using 10 mol% SiO2. The average crystalline size of TiO2 in the films after calcination at 1000 degrees C was about 28 nm. The photocatalytic activities of the films were evaluated based on degradation rates of a methylene blue solution under UV irradiation, and the results revealed that double layered SiO2/TiO2 composite films calcined at 700 degrees C exhibited the highest photocatalytic activity.
Volume:7
Issue:4
Translation or Not:no