Synthesis of TiO2/ZrO2/SiO2 powders and their structural, optical and photocatalytic properties

Ternary oxide powders based on titania, zirconia and silica have been synthesized by the sol–gel method. The characterization of the powders was performed using UV–Vis spectroscopy, EPR, X-ray diffraction and Raman spectroscopy. The XRD study indicated the formation of TiO2 nanocrystals in anatase phase and titanium zirconate as srilankite phase. The band gap energy values of ternary powders are in the range of 3.2–3.3 eV. It is found that different types of paramagnetic centers were formed depending on silica sources after high-energy irradiation. As shown by the electron paramagnetic resonance study, the stability of SiO2 against β-irradiation is observed only for TiO2/ZrO2/SiO2 powder obtained from tetraethoxysilane as well as the formation of oxygen vacancies in TiO2 structure. Photocatalytic activity of TiO2/ZrO2/SiO2 powders is investigated in the process of photoreduction of Cr(VI) ions to Cr(III). As shown, the efficiency of photocatalyst depended on the nature of defect sites of the nanocomposites’ surface. It is found that the TiO2/ZrO2/SiO2 system obtained using tetraethoxysilane exhibited the highest photocatalytic activity as a result of the certain defect sites formation after high-energy irradiation.