TiO2/SiO2 mesoporous microspheres with intelligently controlled texture

Abstract

TiO2/SiO2 mesoporous microspheres with a dense TiO2/SiO2 shell and a highly porous TiO2 core were synthesized in a quasi-emulsion system containing Ti(OBun)4 complex droplets and Si(OC2H5)4 molecules through a hydrothermal process at 150°C. The obtained TiO2/SiO2 microspheres were characterized by scanning electron microscope, transmission electron microscope, X-ray diffractometer, infrared spectrometer, X-ray photoelectron spectrometer and N2 adsorption–desorption isotherms. The thermogravimetric analysis for the hydrothermal intermediates indicates that the difference in the hydrolysis reactivity of Ti(OBun)4 complex and Si(OC2H5)4 results in a suppression effect of TiO2/SiO2 gel shell on the volume shrinkage of TiO2 gel core and leads to the formation of the highly porous microstructure of final TiO2/SiO2 microspheres. As compared with pure TiO2 microspheres, the TiO2/SiO2 microspheres possess high specific surface area and large total pore volume due to the combination of amorphous SiO2 and the novel microstructure of TiO2/SiO2 microspheres and thus show a significantly enhanced adsorption capacity for methylene blue. The high photocatalytic efficiency of TiO2/SiO2 microspheres for the decomposition of methylene blue was mainly attributed to the enhanced adsorption capacity and thus an increase in the capture efficiency of surface-bonded hydroxyl radicals.