Fabrication of TiO2 hollow microspheres using K3PW12O40 as template

Fabrication of TiO2 hollow microspheres (TiO2-HMSs) has attracted considerable attention owing to their low density, high photoreactivity, and easy to separate and reuse. A fluoride-free method for the fabrication of TiO2-HMSs is reported by refluxing a mixed solution of H3PW12O40 (0.4 mmol), KCl (2.5 mmol) and Ti(SO4)2 (2–25 mmol) at 125 °C for 8 h, followed by decomposition of the K3PW12O40 (KPW) template in basic solution. The prepared TiO2-HMSs are characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The activities of the photocatalysts are evaluated by photocatalytic degradation of Brilliant Red X-3B, an anionic dye, under UV irradiation. It is observed that the TiO2-HMSs exhibit diameters of approximately 0.5–1 μm, and the photocatalytic activity of TiO2-HMSs initially increases and then decreases with an increasing amount of Ti(SO4)2. The TiO2-HMSs prepared in the presence of 4 mmol Ti(SO4)2 exhibit the highest photocatalytic activity, which is 2.1 times higher than TiO2 nanoparticles (prepared in the absence of the KPW template). The enhanced photocatalytic activity of the prepared TiO2-HMSs is ascribed to the improved crystallization, coupling effect between TiO2 and the residual KPW template, and the unique hollow structures of TiO2-HMSs.

Graphical AbstractA facile method for the fabrication of high photoreactive TiO2-HMSs is described. K3PW12O40 (KPW) solid microspheres are used as templates, which can be decomposed in the presence of basic solution.Figure optionsDownload as PowerPoint slide