Hydrothermal synthesis of mesoporous TiO2–ZnO nanocomposite for photocatalytic degradation of methylene blue under UV and visible light

Mesoporous ZnO–TiO2 was synthesized successfully by a one-step hydrothermal procedure using titanium sulfate and Zinc nitrate hexahydrate as precursors, and Pluronic P123 as a template. The prepared ZnO–TiO2 materials were heat treated at 400, 600, 800 and 1000 °C to remove the template and increase the degree of crystallization. Field emission scanning electron microscopy, wide angle X-ray diffraction, Fourier transformed infrared spectroscopy, transmission electron microscopy and N2 adsorption–desorption experiments were used to characterize the synthesized powders. Comparison photocatalytic investigations for the prepared materials and commercially available P25 were carried out under identical UV and visible light to understand the effect of the achieved phases and surface area on photocatalytic rate constant and percentage degradation. Results show that the sample which was heat treated at 800 °C (S-800) presents a very high performance under visible light and around 60% of the methylene blue (MB) solution can be degraded by this catalyst in spite of its low surface area. The high efficiency of this sample under visible light can be related to its high degree of crystallinity, formation of anatase and titanium–zinc oxide phases and interfacial coupling between ZnO and TiO2 nanoparticles.