A facile method for the fabrication of SiO2 and SiO2/TiO2 hollow particles using Na2SO4 particles as templates

We present an effective and environmental-friendly pathway to prepare SiO 2 hollow particles using Na 2 SO 4 particles as templates, which involved sol-gel silica coating on surface of the templates and subsequent removal of the Na 2 SO 4 templates by water-dissolution. Further, SiO 2 /TiO 2 double-shell hollow particles were prepared by coating TiO 2 on the surface of the hollow SiO 2 particles. The morphologies and structures of the synthesized hollow particles were characterized using SEM, TEM, XRD, FTIR, BET, and UV. The sizes and shapes of the hollow particles can be controlled by using Na 2 SO 4 templates with different sizes and shapes. The sizes of hollow particles were in the range from 500 nm to 15 μm. By changing the concentration of silicon precursor, the shell thickness of hollow SiO 2 particles can be controlled in the range of 25–200 nm. In addition, SiO 2 /TiO 2 double-shell hollow particles showed better photocatalytic degradation of Rhodamine B than that of hollow TiO 2 particles and solid TiO 2 particles. In this study, we have successfully fabricated hollow SiO 2 particles with different shapes and size, as well as hollow SiO 2 /TiO 2 double-shell particles via a facile and environmentally friendly method employing water-soluble inorganic Na 2 SO 4 particles as template. The preparation process involved sol-gel silica and titania coating on surface of the template and followed by water-dissolution removal of the Na 2 SO 4 template.