Preparation Of Titania Photocatalysts And Their Photoelectrocatalytic Capability

As a semiconductor oxides, TiO2 is a photocatalyst that shows high photoefficiency and oxidation activity. TiO2 has become a hot research area because it can decompose organic pollutants into CO2 and H2O in gases and liquids. Photoelectrocatalysis is a method that applied the bias potential to take away the photoelectrons and decrease the combination of electron-holes. So the method can increase the photoefficiency evidently. The thermodynamically stable rutile TiO2, is commonly thought to have very low catalytic activity, but has a extent exitation wavelengths with broad application. To study how to improve the catalytic activity of rutile TiO2 is very interesting. This study demonstrated the catalytic activity of rutile TiO2 powders, rutile TiO2 films and WO3-TiO2 films in the photoelectrocatalytic degradation of methyl orange. Anatase, rutile and mixed-phase TiO2 powders were made by sol-gel method. Photocatalytic, electrocatalytic and photoelectrocatalytic degradation of methyl orange by the three catalysts showed that the electrocatalytic degradation efficiency of rutile is higher than anatase by 60.9% and the photoelectrocatalytic degradation efficiency is higher by 8.3%, respectively. We prove the conclusion by the electrochemistry experiments. Since the fixed catalysts are more practicable to the treatment of pollutants than the powder catalysts, the study performed the direct thermal oxidation method to prepared rutile TiO2 films. The crystalline texture and morphology of the TiO2 film were examined by X-ray diffractometer and scanning electronic microscopy respectively. The photocatalytic activity of rutile TiO2 films was investigated by the photocatalytic degradation of methyl orange. The results show that the samples calcined at 600 ℃ with 3 h had the highest photoelectrocatalytic activity, the degradation efficiency is 34.8%; and the photoelectrocatalysis is higher than the sum of photocatalysis and electrocatalysis, indicating that there exists a apparent photoelectrochemical synergic effect. The electron acceptors which were added to the photoelectrocatalytic processes enhanced the catalytic activity obviously. To obtain better photocatalytic activity of rutile TiO2 films, WO3-TiO2 composite photocatalysts were prepared on the surface of rutile TiO2 films. It was found that the WO3-TiO2 composite photocatalysts calcined at 500 ℃ for 1h with 3% of WO3 showed higher photocatalytic activity than that of pure TiO2 film by 85.7%. The results also indicated that theaddition of appropriate WO3 could effectively decrease the development temperature of rutile phase.