Synthesis and Characterization of Size-Controlled TiO2 Microspheres with Wormhole Mesoporous Structure

The size-controlled TiO2 microspheres with wormhole mesoporous structure have been synthesized via a salt-assisted sol-gel method. The influences of various precursor concentrations and the addition of different salt ions on the size and on the size distribution of the final microspheres were investigated. Structural characterization indicates that these TiO2 microspheres with the diameters of 60 nm-2 mu m are composed of nanocrystals (about 12.8 nm), while their aggregate size is controlled by the addition of salt solution. The TiO2 microspheres after calcined at 500 degrees C have an obvious wormhole mesoporous structure. The mesoporosity is mainly due to the interparticle porosity. A possible formation mechanism for mesoporous TiO2 microspheres is discussed.