Influence of preparation method on the physicochemical properties and catalytic activity of SiO2–TiO2 mixed oxides

Abstract

In this study, SiO2–TiO2 mixed oxides with different physicochemical properties and various activities were prepared by sol–gel method under acid-catalyzed and base-catalyzed conditions. X-ray diffraction (XRD), scanning electron microscope, and energy dispersive X-ray spectroscopy (EDX) analysis methods were used for the characterization of prepared samples. The photocatalytic activity was evaluated vs. the decolorization of methyl orange (MO) under black-light radiation. The influence of synthesis method on the physicochemical properties such as crystalline structure, crystal size, morphology, and photocatalytic activity of samples was investigated. The XRD patterns showed that the sample prepared by sol–gel method under acid-catalyzed conditions has pure anatase phase, whereas the sample prepared by sol–gel method under base-catalyzed conditions has anatase-rutile mixed phase. SiO2–TiO2 mixed oxides prepared under acid-catalyzed conditions showed higher photoactivity in comparison with SiO2–TiO2 mixed oxides prepared under base-catalyzed conditions for the sake of reducing the crystallite size and agglomerations. The figures-of-merit based on electric energy consumption (electrical energy per order (EEO)) were evaluated in the photodecolorization of MO in the presence of prepared samples. The results showed that less energy is consumed during the decolorization of MO in the presence of SiO2–TiO2 mixed oxides prepared by sol–gel method under acid-catalyzed conditions.