2.2. Synthesis of nanosize TiO2
All the chemical reagents in this study were of reagents grade
and used without further purification. The nanoscale TiO2 used in
this experiment was prepared by a sol–gel method [23]. 30 mL
butyl titanate and 20 mL ethyl alcohol were firstly mixed by magnetic
agitating, and then dropwised by 100 mL water solution with
ethyl alcohol (25 mL) and acetic acid (25 mL) under stirring. Subsequently,
the mixture was stewed for 1 h followed by ultrasonic
purifying of 15 min, and then the solution was dried at 80 C for
12 h. Finally, the film was calcined at 500 C for 1 h to transfer
amorphous TiO2 to nanostructure.