TiO₂-ZnO Binary Oxide Systems: Comprehensive Characterization and Tests of Photocatalytic Activity

A series of TiO₂-ZnO binary oxide systems with various molar ratios of TiO₂ and ZnO were prepared using a sol-gel method. The influence of the molar ratio and temperature of calcination on the particle sizes, morphology, crystalline structure, surface composition, porous structure parameters, and thermal stability of the final hybrids was investigated. Additionally, to confirm the presence of characteristic surface groups of the material, Fourier transform infrared spectroscopy was applied. It was found that the crystalline structure, porous structure parameters, and thermal stability were determined by the molar ratio of TiO₂ to ZnO and the calcination process for the most part. A key element of the study was an evaluation of the photocatalytic activity of the TiO₂-ZnO hybrids with respect to the decomposition of C.I. Basic Blue 9, C.I. Basic Red 1, and C.I. Basic Violet 10 dyes. It was found that the TiO₂-ZnO material obtained with a molar ratio of TiO₂:ZnO = 9:1 and calcined at 600 °C demonstrates high photocatalytic activity in the degradation of the three organic dyes when compared with pristine TiO₂. Moreover, an attempt was made to describe equilibrium aspects by applying the Langmuir-Hinsherlwood equation.