Investigation of Zinc-Doped Titanium Nanocomposites and Their Photocatalysis Effectiveness

Abstract TiO2 nanocomposites doped with Zn have been prepared via the sol-gel method. These nanocomposites with various doping percentages exhibited multi-phase structures with promising photocatalytic efficiency for the removal of pollutants, manifested by methylene blue degradation. Common characterization techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and UV–Vis spectroscopy, were employed to characterize the prepared samples. The identified phases are the rutile tetragonal and wurtzite hexagonal crystal structures of TiO2 and ZnO, respectively, while the doped samples tend to exhibit multi-phase structures of rutile, anatase, zincite, spinal, and inverse spinel cubic phases. Doping significantly influenced the energy gaps, which ranged from 2.9 eV to 3.45 eV. SEM morphological studies confirmed that the average size of the nanoparticles was around 150 nm, while the size of the crystallites varied with doping, ranging from 18 nm to a maximum of approximately 42 nm at a 5 wt% of Zn doping, which is manifested as the optimal doping amount that enhanced the properties of the nanocomposite. However, further increases in doping concentration resulted in the creation of additional scattering centers, which negatively impacted photocatalytic efficiency. The optimal doping ratio resulted in a photocatalytic efficiency of about 98%.