Fig. 4a showed the SEM images of the pulverous TiO2 which was
synthesized by sol–gel method and calcined at 500 C for 1 h. The
low magnification figures showed that a large number of small
holes existed on the surface. and these powders were firmly coagulated
each other to a clumpy surface layers of nanocages, the high
magnification figures confirmed that the nanoparticle size had an
irregular diameter distribution. In order to explore more accurate
composition, the TEM images of analyte were achieved in Fig. 4b.
It was exactly demonstrated that the constitution of each product
element was irregular spherical, with the particle size ranging from
50 to 200 nm. Because of the specific morphology and structure,
the catalytic ability of TiO2 could be motivated within a radiation
light, the ability of directional transmission and inspiration for
active molecules was increased, so the target pollution could be
degraded effectively [25].