Anatase TiO2 sols were synthesized under mild conditions (i.e. 75 1C and ambient pressure) by hydrolysis of titaniumn-
butoxide in abundant acidic aqueous solution and subsequent reflux to enhance crystallization. The influences of
various acidities on crystallinity, morphology, and size of the obtained TiO2 sol particles were investigated. At room
temperature and in ambient atmosphere, crystalline TiO2 thin films were deposited on quartz glass slides from the asprepared
TiO2 sol by a dip-coating method. TiO2 films on substrates could be thickened by means of consecutive dipcoating
processes. The photocatalytic activities of the TiO2 thin films were assessed by the degradation of X-3B in
aqueous solution under aerated conditions. The preparation process of photocatalytic TiO2 thin films was quite simple
and a low-temperature route.