Effects of Heat Treatment on Photocatalytic Property of Sol-Gel Derived Polycrystalline TiO2

Polycrystalline TiO₂ in the bulk form was prepared by hydrothermal treatment of amorphous TiO₂ gel, and its photocatalytic activity for degradation of ethanol and physical properties were investigated after drying and calcination (300–650°C). The maximum photocatalytic activity reached when the polycrystalline TiO₂ was calcinated at temperatures from 300 to 500°C, which was almost the same as for a commercial TiO₂ powder. It was markedly reduced above 600°C. Photocatalytic activity of TiO₂ was affected by crystal growth of anatase, progress of sintering, anatase-rutile transformation and morphology of the polycrystalline TiO₂. It was a characteristic of the polycrystalline TiO₂ prepared in this study that the photocatalytic activity did not vary so much with the calcination temperature in the range of 300–500°C.