Effect of annealing temperature on the structural, optical and photocatalytic activity of TiO2 thin films by chemical bath deposition technique

In this report, we have synthesized nanocrystalline of TiO2 thin films by simple chemical bath deposition technique. The as-deposited films were annealed at different temperatures (300, 500 and 700 °C) for 5 h in ambient atmosphere in order to improve crystallinity and structural perfection. The structural, morphological and optical properties were analyzed by using X-ray diffraction (XRD), Atomic force micrograph, Fourier Infrared spectra, UV–Vis transmission spectra and photoluminescence (PL) spectra analysis. XRD results showed that formation of anatase phase for all the annealed samples. The average crystalline size was found to be increased from 35 nm to 46 nm with increasing the annealing temperature. Band gap energy of the 300 °C sample was found to be 3.42 eV, further it was decrease to 3.33, 3.27 eV for 500 and 700 °C annealed samples respectively. The decreasing in the band gap energy and oxygen related vacancies were analyzed by PL analysis. The photocatalytic activity of the TiO2 films were studied by monitoring the degradation of methylene blue rhodamine B in an aqueous solution under visible light irradiation and were empirical that TiO2 film 700 °C samples exhibited excellent photocatalytic activities, when compared with other TiO2 film.