Preparation And Study Of Photocatalytic Titanium Dioxide Anatase High Activity

In1972, Fujishima and Honda discovered the phenomenon of photocatalytic splitting of water on a TiO2electrode under ultraviolet (UV) light. Since then, enormous efforts have been devoted to the research of TiO2material. Since its commercial production in the early twentieth century, titanium dioxide (TiO2) has been widely used.As the most promising photocatalyst, TiO2materials are expected to play an important role in helping solve many challenges. The photocatalytic activity of semiconductor materials must be controlled by these basic parameters:(1)light absorption property,(2)rate of reduction and oxidation of reaction substrate by respectively e-and h+, and(3)rate of e--h+recombination. The first parameter is mostly governed by the bulk structure of the semiconductor solid and if we choose one of the crystal forms of the photocatalyst, it is more difficult to modify. The second parameter has received much attention of researchers in this field of chemistry. Redox potential of the reaction substrates may be influenced slightly by the surface chemical structure, but the amount of adsorbed substrate depends more directly on the nature of the surface, e.g., specific surface area. Thus, the second parameter is closely related with the surface area. The third parameter has been neglected, partly because its estimation is rather difficult compared with the other two parameters. However, it has been proved that the recombination rate predominates the photocatalytic activity in some photocatalysts or under selected reaction conditions.As described above, the rate of e"-h+recombination must be an decisive factor in photocatalytic activity,since the photogenerated e--h+pairs recombine to give no chemical reactions.We can control the crystallinity and shape of titanium dioxide to inhibit the recombination of e--h+pairs.In this report, we obtained decahedral anatase TiO2nanocrystals by H2O2-NH3Solution. The results showed that the ratio of H2O2and NH3, the pH of solution, reaction temperature and time have great influence on the size and shape of the titanium dioxide particles. Decahedral titanium dioxide particles have higher activity than other irregular shape particles. At the same time, we find that a moderate amount of defect can enhance the activity of titanium dioxide.