Porous TiO2 Photocatalyst Films Prepared from Peroxo Titanic Acid Solution Dispersing Nano-Sized Silicate Layer

The (silicate layer)/TiO2 composite sols were synthesized by the hydrothermal treatment of peroxo titanic acid (PTA) solution containing dispersed silicate layers (SL) of smectite clay (SM). The SM content changed from 0 to 30 wt%. PTA polymerized to anatase TiO2 by the hydrothermal treatment between 130DGC-160DGC in the case of SM mixture. The pure TiO2 sol showed a wide range size of 1-20 *mm. The SM (30wt%)/TiO2 sol, however, has the narrow size distribution, #~10 *mm. The resulting sols were spin-coated on glass plates and heat-treated at 400DGC for 0.5 h. The crystallite size of TiO2 decreased with increasing SM content. The wettability of SL/TiO2 sol to the glass decreased with increasing SM content. The photocatalytic activity of the TiO2 film was evaluated by measuring the amount of the decomposed methylene blue (MB) in the solution during UV light irradiation. The specific surface area of SL/TiO2 film increased with the SL content due to the smaller particle size and the incorporation of SL. Therefore, the amount of the adsorbed MB increased with increasing SM content. SM(30wt%)/TiO2 film showed the highest photocatalytic activity due to its high ability of the MB adsorption.