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In this study, we showed that the TiO 2 thin films deposited onto window glass are practicable for air purification and self-cleaning applications. TiO 2 films were deposited onto window glass by ultrasonic spray pyrolysis method. Different deposition temperatures were used in the range of 250–450°C. The structural, morphological, optical properties and surface chemical composition were investigated to understand probable factors affecting photocatalytic performance and wettability of the TiO 2 thin films. The TiO 2 thin films were smooth, compacted and adhered adequately on the substrate with a thickness in the range of 100–240 nm. X-ray diffraction patterns revealed that all the TiO 2 thin films consisted of anatase phase structure with the mean crystallite size in the range of 13–35 nm. The optical measurements showed that the deposited films were highly transparent (approx. 85%). The wettability test results showed that the TiO 2 thin films sprayed at 350°C and 450°C and annealed at 500°C for 1 h were superhydrophilic. The photocatalytic activity of the films was tested for the degradation of methyl tert-butyl ether (MTBE) in multi-section plug-flow reactor. The TiO 2 film deposited at 350°C exhibited the highest amount of conversion of MTBE, approximately 80%.

TiO2 thin films with different titanium isopropoxide (TTIP):acetylacetone (AcacH) molar ratios in solution were prepared by the chemical spray pyrolysis method. The TTIP:AcacH molar ratio in spray solution varied from 1:3 to 1:20. TiO2 films were deposited onto the glass substrates at 350 °C and heat-treated at 500 °C. The morphology, structure, surface chemical composition, and photocatalytic activity of the obtained TiO2 films were investigated. TiO2 films showed a transparency of ca 80% in the visible spectral region and a band gap of ca 3.4 eV irrespective of the TTIP:AcacH molar ratio in the spray solution. TiO2 films consist of the anatase crystalline phase with a mean crystallite size in the range of 30–40 nm. Self-cleaning properties of the films were estimated using the stearic acid (SA) test. A thin layer of 8.8-mM SA solution was spin-coated onto the TiO2 film. The degradation rate of SA as a function of irradiation time was monitored by Fourier-transform infrared spectroscopy (FTIR). An increase in the TTIP:AcacH molar ratio from 1:4 to 1:8 resulted in a ten-fold increase in the photodegradation reaction rate constant (from 0.02 to the 0.2 min−1) under ultraviolet light and in a four-fold increase under visible light.

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The photocatalytic oxidation of humic substances in aqueous solutions and natural waters with TiO 2 attached to buoyant, hollow glass micro-spheres was studied. A maximum oxidation efficiency of 3.6 mg W 1 h 1 was achieved in neutral or alkaline media at a plane surface concentration of the catalyst attached to the micro-spheres of 25 g m 2 . Proceeding by different mechanisms in acidic and alkaline media, the photocatalytic oxidation efficiency did not benefit from an excessive presence of hydroxyl radical promoters, hydrogen peroxide and alkali.