M Fazlali - Department of Physics, Sharif University of Technology, ۱۱۱۵۵-۹۱۶۱, Tehran, Iran
M Amiri
A. Z. Moshfegh

In recent years, the process of heterogeneous photocatalysis, especially with the use of TiO2 as a catalyst, has been extensively studied in the purification of water and wastewater. This is because almost all organic pollutants, including those toxic at low concentration, can be decomposed to carbon dioxide with the strong oxidizing power of the photogenerated holes of TiO2 [1]. However, this technique is insufficient for practical application due to the rapid recombination of active electrons and holes after photoexcitation. To further improve the efficiency of photocatalytic (PC) oxidation reactions, the TiO2 catalyst can be modified by the addition of various impurities. For example, different metals or metallic oxides can be added either into the TiO2 structure by doping, implanting or coprecipitating or onto the TiO2 surface by coating or photodepositing as metal islands [2,3]. On the other hand a few approaches have been explored in order to improve the photocatalytic activity by using bilayers in order to increase the electron-hole recombination time. As the literature survey, TiO2 and ZnO are the most widely used photocatalysts but they require UV-light for activation; solar UV light reaching the earth surface is relatively small. On the other hand, the band gap energy of Fe2O3 is 2.2 eV and can be activated with visible light (<560 nm); Thus Fe2O3 photoelectrode can be used as a solar energy conversion material [4,5].In the present paper, Fe2O3/TiO2 bi-layers photocatalytic activity was investigated by methylen blue (MB) photocatalytic degradation reaction under visible light, photoactivity of Fe2O3/TiO2 catalyst was precisely evaluated. We have investigated the effect of different thickness of Fe2O3 layer on photoactivity of the Fe2O3/TiO2 nanocatalyst.