Good photocatalytic activities of TiO2 films
necessitate (a) an efficient photo-induced electron–
hole pair generation, and (b) an efficient
charge separation, which requires in turn preparations
of well-crystallized TiO2 films, preferably in
the anatase crystalline form [2,3].
A variety of physical and chemical approaches
have been used for TiO2 thin-film preparation. The
sol–gel technique has emerged as one of the most
promising techniques for growing TiO2 thin films.
However, since the crystallization of amorphous
sol–gel derived TiO2 films requires a subsequent
thermal treatment at relatively high temperature,
photocatalytic applications are essentially forbidden
to substrates of low thermally resistant
materials such as plastics. Therefore, it will be
very interesting and challenging to prepare wellcrystallized
TiO2 nanoparticles at low temperatures.