Understanding the solar photo-catalytic activity of TiO2–ITO nanocomposite deposited on low cost substrates

In this work, we report on the photo-catalytic properties of TiO2–ITO nanocomposite deposited on low cost conventional clay ceramic substrates. The nanocomposite was formed by spraying a solution prepared from the P25 TiO2 powder (Degussa) mixed with an organometallic paste of a dissolved combination of indium and tin. A TiO2–ITO powder-like nanocomposite was prepared for X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterization. The mean particle size of the TiO2–ITO nanocomposite was found to be larger than that of pure TiO2. The optical features of TiO2–ITO-based layers (deposited on glass substrates) were investigated using UV–vis spectroscopy. The TiO2–ITO nanocomposite deposited layers were found to have higher light absorption than the P25 TiO2 powder. The photo-catalytic properties of the TiO2–ITO nanocomposite (deposited on low cost clay ceramic substrates) were tested under solar irradiation using a well-known polluting dye. It was shown that the TiO2–ITO nanocomposite exhibits higher degradation rates towards the pollutant dye than the P25 TiO2 powder. The optical band gap of the TiO2–ITO nanocomposite (2.79 eV) was found to be lower than that of pure TiO2 (3.1 eV), while ITO (indium tin oxide) has a band gap of about 4.2 eV. ITO was found to be entirely transparent to sun light, while it exhibits a slight photo-catalytic activity, signifying the possible existence of an indirect photo-catalysis phenomenon (sensitized semiconductor photocalysis) and potential degradation (oxidation) of the pollutant through electron transfer from the dye to conduction band of the semiconductor. All photo-catalytic activity results were discussed in light of the optical band gap of the various compounds.