Photocatalytic Oxidation of Pesticides with TiO2-CeO2 Thin Films Using Sunlight

Abstract

TiO2 thin film coatings significantly improve catalyst separation in photocatalytic processes. They can be applied in heterogeneous photocatalysis under sunlight by mixing TiO2 with other oxides, such as CeO2, for the removal of pollutants in water. Here, TiO2-CeO2 thin films deposited on borosilicate slides were analyzed and applied in solar heterogeneous photocatalysis for the oxidation of pesticides. The films were synthesized by the sol-gel method with spin coating. The waste solutions from the synthesis were used to prepare TiO2 and TiO2-CeO2 powders. These were analyzed by XRD and XPS to explain the behavior of the films. The thin films were characterized by UV-Vis spectroscopy with transmittance, UV-Vis spectroscopy with RDS, profilometry, AFM and SEM. The addition of CeO2 to TiO2 caused a decrease in the average crystal size and an increase in the strain index. The addition of a second layer made the TiO2-CeO2 thin films thinner. The CeO2 created surface and electronic defects in the titania films, which enhanced their photocatalytic properties under sunlight in the mineralization of diuron and methyl parathion. The TiO2-CeO2-5.0% single-layer thin film samples were the most active in this study and will undoubtedly be applied in larger-scale reaction systems.