A facile and low cost synthesis of multifunctional AZO thin films for rapid and effective removal of Orange II dyes under sunlight irradiation.

Al doped ZnO multifunctional thin films (AZO) were successfully prepared by sol-gel method on small porous ceramic substrates. The effects of Al doping on the microstructural, morphological, optical and photocatalytic properties of the films were investigated. The XRD analysis detected the polycrystalline structure with wurtzite-type for all synthesized samples. The grain size was found to vary between 20 nm and 30.8 nm. UV-Visible absorbance data indicated that all AZO films absorb visible light at around 485 nm. In addition, a blue shift toward shorter wavelengths side was noted with increasing Al content up to 5%, while the band gap showed an increasing trend achieving 3.28 eV. SEM analysis showed that Al dopants greatly affected the morphology of ZnO samples. Moreover, Al doping was found to enhance the adsorption capacity of ZnO for OII dye up to 37%, which accelerated the photodegradation process of the samples. The highest value of the color removal efficiency of residual dye molecules, 78.5%, was observed for AZO (5% Al). The highlighted results indicated that the sol-gel dip coated AZO films are attractive and suitable for water treatment through both photocatalytic and adsorption activities. [ABSTRACT FROM AUTHOR]