Study On The Preparation And Photocatalytic Activity Of TiO₂

The TiO₂ have been deposited on glass using water as solvent by sol-gel processing; theTiO₂ films are treated by microwave (MW) plasma. TiO₂ films treated by MW plasmas showa high activity in ultraviolet (UV) and visible region. The experimental results andconclusions are summarized as follows:(1) The sol for TiO₂ films was prepared with tetrabutyl titanate as prescursor, water assolvent, and nitride acid as catalyst. TiO₂ films are obtained by dip-coating method. Thephotocatalytic activity of the prepared films is studied by the degradation of stearic acid. Andthe TiO₂ films have a high photocatalytic activity without further thermal treatmem. It isimportant to form TiO₂ film with photocatalytic activity at low temperature on nonthermalresisted substrates. The sol was prepared at different temperature, drying them to gain TiO₂powder, then calcining TiO₂ powder at 450℃. The result shows that the content of rutile TiO₂in the sample decreases with increasing the temperature.(2) Nitrogen MW-plasma was used to elevate photocatalytic activity of the as-grown films.In this work, the flow rate of nitrogen was fixed at 120 sccm and the microwave powerdelivered to the plasma was 250 W. The treatment time was 5 min. The photocatalytic activityof MW-plasma-treated films was enhanced. And the results in the case of an 8-cycleexperiment show a good stability of the treated films. The treated films show visible-lightabsorption in the range of about 400-600 nm. Therefore, thermally unstable materials can besubstrates; only the skin layer of the substrate is modified with no deterioration of the bulkmaterial.