Study of rutile-supported anatase nanostructured films as photocatalysts for the degradation of water contaminants

Abstract

This dissertation studies the application of rutile substrate as an alternative support for anatase films, specifically, on the growth and properties of anatase films. The films were utilized as catalysts for the photodegradation of water contaminants (Atrazine and Rhodamine B). Ti4+ precursor resin was prepared by the polymeric precursor method and deposited by spin coating onto polycrystalline rutile and rutile coated glass substrates. The films were calcined at different temperatures (350 °C to 500 °C) to form anatase TiO2 films. The influence of temperature on the properties of the films has been reported in this study. A comparative study of the films was also done using X-ray diffraction technique (XRD), grazing incidence X-ray diffraction (GIXRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). XRD and GIXRD results confirmed the formation of anatase on the (101) plane depending on the calcination temperature. Bandgap modification of the films with respect to calcination temperature was measured by UV visible diffuse reflectance spectroscopy. The bandgaps were in the range of 2.74 to 2.85 eV. Photocatalytic activity of the films supported on rutile substrate was studied for the degradation of Atrazine (ATZ) and Rhodamine B (Rhod-B) under UV light. Further, the stability of the films was evaluated on four consecutive cycles where the films maintained their photocatalytic properties in all cases. The kinetics of Rhod-B and ATZ degradation followed a pseudo first order and first order exponential decay respectively. The films calcined at 450 °C and 500 °C showed superior photocatalytic activity for Rhod-B degradation than the films calcined at 350 °C and 400 °C. This is attributed to the adequate crystallinity of anatase. For ATZ degradation, the films were also efficient but no specific trend was observed. The results can contribute towards the development of TiO2 films on rutile phase substrates.