Photodegradation of sunset yellow by TiO2/SnO2 nanocomposites films deposited using spray pyrolysis

Abstract

The main objective of the work in hand is to investigate the degradation of sunset yellow dye under UV light using the TiO2 and SnO2 as photocatalysts. Thin films of TiO2 (T), SnO2 (S) and their nanocomposite (TS) were eposited by spray pyrolysis on glass substrate at 550 °C. According to X-ray diffraction (XRD), all the films had a polycrystalline structure. The S film had traces of SnO and the T film was a mixture of anatase and rutile. The TS film was a combination of anatase, rutile and SnO2. The grain size decreased from 115 nm in S to 21.5 and 18.8 nm in T and TS films respectively. Tensile strain was present in all films. The UV-Vis spectra revealed relatively higher transmittance in TS and T and lesser in S. Using the Tauc plot, the optical gap energy was calculated to be 3.60, 3.17 and 3.71 eV for S, T and TS respectively. The surface morphology examined by SEM showed homogenous grain with different shapes and sizes. The photodegradation of sunset yellow dye after 18 hours was ameliorated in the TS film to reach 90.27% where the S and T films had 19.74 and 29.65 degradation percentage respectively. The photocatalysis kinetics was found to fit a first order chemical reaction.