Photocatalytic degradation of malathion in aqueous solution using an Au-Pd-TiO2 nanotube film

The extensive use of pesticides has promoted the agricultural production, but a series of subsequent environmental issues have drawn the concern of governments and people worldwide, such as groundwater and surface water pollutions. In order to remove these pollutants, photocatalysis has emerged as a powerful method. In this paper, the photocatalytic degradation of an organophosphorus pesticide malathion was investigated using an Au-Pd co-modified TiO2 nanotube film (Au-Pd-TiO2). This film was fabricated by simultaneously photo-depositing Au and Pd precursors on a self-organized TiO2 nanotube film. Its morphology and structures were well characterized by a scanning electron microscope (SEM), X-ray diffraction (XRD). and X-ray photoelectron spectroscopy (XPS). The photocatalytic experiments revealed that the malathion elimination rate increased by 172% when the photocatalyst of the naked TiO2 nanotube film was replaced by Au-Pd-TiO2. Additionally, the amount of H2O2 yielded on the Au-Pd-TiO2 film in 60 min was 2.89 times that on the naked TiO2. The enhanced photocatalytic performance could be attributed to both the effective separation of photo-generated charge carriers and the higher synthesis rate of H2O2. The possible photocatalytic mechanism was discussed. (C) 2010 Elsevier B.V. All rights reserved.