Ultrasonic-assisted sol–gel synthesis of TiO2 nanostructures: Influence of synthesis parameters on morphology, crystallinity, and photocatalytic performance

Abstract

The influence of synthesis parameters using the ultrasonic-assisted sol–gel method on the properties of TiO2 nanostructures was studied. Different synthesis conditions such as long stirring time, type of acid used as the catalyst (weak or strong acid), and calcination temperature were explored and their influences on the morphology, size, crystallinity of nanostructures, and photocatalytic performance were evaluated. TiO2 nanostructures were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray diffraction, and ultraviolet–visible diffuse reflectance spectroscopy. Moreover, degradation photocatalytic tests were performed using methylene blue as the polluting model. Changes in the morphologies and sizes of nanostructures were observed by modification of the stirring time using this sonication process. Moreover, the use of a weak acid, such as acetic acid, produced nanostructures with higher anatase proportion, larger crystallite size, and larger nanoparticle size compared with the use of a strong acid such as nitric acid. In addition, changes in crystalline phases were observed with an increase in the calcination temperature. Finally, the photocatalytic performance was influenced mainly by the changes in the crystalline phases, which were dependent on the type of acid catalyst and the calcination temperature.