Effects of heat treatment on photocatalytic property of sol-gel derived polycrystalline TiO2

Polycrystalline TiO2 in the bulk form was prepared by hydrothermal treatmen t of amorphous TiO2 gel, and its photocatalytic activity for degradation of ethanol and physical properties were investigated after drying and calcina tion (300-650 degreesC). The maximum photocatalytic activity reached when t he polycrystalline TiO2 was calcinated at temperatures from 300 to 500 degr eesC, which was almost the same as for a commercial TiO2 powder. It was mar kedly reduced above 600 degreesC. Photocatalytic activity of TiO2 was affec ted by crystal growth of anatase, progress of sintering, anatase-rutile tra nsformation and morphology of the polycrystalline TiO2. It was a characteri stic of the polycrystalline TiO2 prepared in this study that the photocatal ytic activity did not vary so much with the calcination temperature in the range of 300-500 degreesC.