Novel raspberry-like hollow SiO2@TiO2 nanocomposites with improved photocatalytic self-cleaning properties: Towards antireflective coatings

Uniform raspberry-like hollow SiO2@TiO2 composite nanospheres (hSiO2@TiO2) have been designed and prepared via a colloidal assembly method. Series of characterizations, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, thermogravimetry, and derivative thermogravity, have been carried out to analyze the composition, structure and morphology of the composite. The dispersion of TiO2 nanoparticles on the outer shell of hollow SiO2 (hSiO2) nanospheres could be effectively tuned via employing H2O2 as a hydroxyl modifier to repair the SiO bonds of the hSiO2. The effects of silanol content of hSiO2 and the Si/Ti ratios were investigated in detail. This unique structure with refractive index of 1.218 and transmittance over 99% exhibited excellent self-cleaning capability when served as antireflective coatings.