Photocatalytic degradation study of methylene blue by brookite TiO2 thin film under visible light irradiation

In the present study, the nanoparticles of TiO2 thin films have been deposited onto ultrasonically cleaned glass substrates by sol gel spin coating technique and annealed at various temperatures (from 300 degrees C to 500 degrees C). Photocatalytic activity of TiO2 film has been studied by photocatalytic degradation of methylene blue (MB) in aqueous solution as a model pollutant under visible light irradiation. The photocatalytic degradation efficiency of MB using TiO2 was reached to 92% after 240 min. XRD analysis confirms that the film was found to be orthorhombic structure and the average crystallite size was found to be in the range of 54 to 67nm. The SEM images of the TiO2 film was shown highly uniform, crack free and having nano spherical particles of average diameter around 68nm. TiO2 thin film exhibits high transparency in the visible region and decrease the optical transmittance with an increase in annealing temperature. Band gap energy calculated using Tauc method and the direct optical band gap of TiO2 film was found to be in the range of 3.3 to 3.48 eV. The Urbach energy of the film tends to increase with increasing annealing temperature. (C) 2016 Elsevier Ltd. All rights reserved.