Effect of the sonication and coating time on the photocatalytic degradation of TiO2, TiO2-Ag,and TiO2-ZnO thin film photocatalysts

Abstract

Today, the ultrasound utilizing for material synthesis has been extensively investigated. The unusual acoustic cavitation phenomenon caused by ultrasonic waves has created a new world for the production of high efficiency photocatalysts with new structures. In this study, TiO₂, TiO₂-Ag, and TiO₂-ZnO thin film photocatalysts were prepared using titanium isopropoxide Ti[OCH(CH₃)₂]₄, zinc acetate dehydrates (CH₃COO)₂Zn·2H₂O, and silver nitrate AgNO₃ by a sol–gel method under the ultrasonic irradiation. The prepared photocatalysts were characterized by UV–vis diffuse reflectance spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), and energy dispersive spectroscopy. The SEM images showed that the Ag and ZnO particles were evenly dispersed in the photocatalysts due to the ultrasonic irradiation, and Ag particles were approximately 90?nm, which is relatively small compared to the photocatalysts which is not treated with ultrasonic irradiation. The catalytic activity of the photocatalysts was determined using Acid Red 27 dye. The most excellent catalytic degradation was obtained with TiO₂-ZnO thin film photocatalyst. In comparison to the conventional photocatalyst, the efficiency of photocatalytic activity of the photocatalyst produced under ultrasonication has been increased due to the reduced size of Ag and ZnO and its uniform dispersion.