Nano synthesis of ZnO–TiO2 composites by sol-gel method and evaluation of their antibacterial, optical and photocatalytic activities

Abstract

85ZnO–15TiO2, 75ZnO–25TiO2, and 65ZnO–35TiO2 nanocomposites were prepared by the sol-gel method. The structural, morphological, antibacterial, optical and photocatalytic performances were analyzed. Three phases, i.e., hexagonal wurtzite, anatase, and hexagonal ZnTiO3 were detected for each of the specimens. The crystallite size reduced as the TiO2 content increased, whereas the corresponding values for 65ZnO–35TiO2 were 39.02 nm (ZnO), 20.40 nm (anatase) and 34.89 nm (ZnTiO3). A particle size reduction phenomenon was observed as approaching from 85ZnO–15TiO2 (66 nm) to 65ZnO–35TiO2 (47 nm). The antibacterial activity was measured through the inhibition of the growth of Escherichia coli bacteria by ZnO–TiO2. The maximum inhibition zone for bacterial growth was achieved for 65ZnO–35TiO2 (19.7 mm). Two types of absorption bands were obtained within the UV–Visible region. However, the blue shifting of these bands resulted in the enhanced band gap. Moreover, 65ZnO–35TiO2 demonstrated the highest photodegradation efficiency of methylene blue dye backing the reason for the lowest particle size (47 nm). The photodegradation efficiency values of 85ZnO–15TiO2, 75ZnO–25TiO2 and 65ZnO–35TiO2 at 100 min were 72.9%, 80.2%, 90.7% respectively.