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.