Ethylene photo-oxidation on copper phthalocyanine sensitized TiO 2 films under solar radiation

Limited solar photo-activity and recovering the catalysts after photocatalysis reaction are two major drawbacks of the highly active TiO2 powder materials. In this study we propose that copper phthalocyanine (CuPc, Cu(II) tetrakis[4-(2,4-bis-(1,1-dimethylpropyl)phenoxy)]phthalocyanine), which is an metal-organic dye could be used as sensitizer of TiO2 coating to shift the absorption band toward visible light. TiO2 coating was applied inside the Pyrex glass tubes and used in the photocatalytic decomposition of ethylene gas under solar light irradiation. Two-step draining method was employed to apply the coating on the inner side of the glass tubes. At first pure TiO2 coating was prepared from a solution by dispersing the commercial P25 TiO2 powders in a TiO2 sol made by hydrolysis-condensation of titanium alkoxide. A controlled draining method was employed to coat the inner side of the glass tubes. After calcination at 500 °C, P25 powders were strongly attached on the glass surface as a thick coating. Visible light absorptive coating was prepared by applying a thin layer of CuPc that shows intense absorption in the visible wavelength region utilizing the same coating procedure. CuPc coated TiO2 film showed excellent photo-stability against solar radiation. Greater photo-oxidation rate of ethylene was achieved with the CuPcTiO2 coated glass tube compared to that without CuPc coating due to the enhanced solar light absorption.