Nanostructured TiO2 thin films prepared by RF magnetron sputtering for photocatalytic applications

Abstract

Nanostructured TiO2 thin films deposited on silica glass substrates were prepared by RF magnetron sputtering combined with thermal annealing. The effects of film thickness on the morphological, structural, optical and photocatalytic properties of the prepared nanostructured TiO2 thin films were investigated. The morphological evolution of the TiO2 thin films with change in film thickness was studied by field emission scanning electron microscopy and atomic force microscopy, while their structural properties were investigated using Raman spectroscopy. The optical and photocatalytic properties of the nanostructured TiO2 thin films were studied using UV–vis absorption spectroscopy. The surface morphology and band gap of the prepared nanostructured TiO2 thin films were found to vary with change in film thickness. Sun light driven photocatalytic degradation of methylene blue (MB) dye in water was used for evaluating the photocatalytic activity of the nanostructured TiO2 thin films. We have demonstrated that the photocatalytic activity of nanostructured TiO2 thin films can be easily tuned by varying the film thickness. Results showed that the nanostructured TiO2 sample prepared using 40nm thick TiO2 film exhibits maximum photocatalytic activity leading to complete degradation of 2.1μM MB in only 45min, which is very promising for practical photocatalytic applications. The observed highly enhanced photocatalytic activity of nanostructured TiO2 sample prepared from 40nm thick TiO2 film is ascribed to its smaller band gap and enhanced absorption of light in the UV–vis region leading to improved utilization of sun light.