TiO₂ thin films by ultrasonic spray pyrolysis as photocatalytic material for air purification

In this study, we showed that the TiO₂ thin films deposited onto window glass are practicable for air purification and self-cleaning applications. TiO₂ 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 TiO₂ thin films. The TiO₂ 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 TiO₂ 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 TiO₂ 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 TiO₂ film deposited at 350°C exhibited the highest amount of conversion of MTBE, approximately 80%.