Effect of pH on the Formation of Amorphous TiO₂ Complexes and TiO₂ Anatase during Pyrolysis of Aqueous TiCl₄ Solution

The TiO₂ nanostructures resulted by pyrolysis of TiCl₄ at low temperature of 80 ^oC are found to be a mixture of amorphous TiO₂ complexes and anatase nanostructure whose ratio depends on the pH of the pyrolysis medium. At low pH level, the resulting TiO₂ nanostructure is predominant anatase and gradually shifts to the amorphous TiO₂ complexes with pH level increasing. By means of heat treatment, the amorphous TiO₂ complexes can be converted back to the anatase nanostructure and then transform to rutile with the elevating temperature. Amongst of the TiO₂ nanostructure recovered from amorphous TiO₂ complexes, the anatase shows to be the most effective photocatalyst in decomposition of methylene blue.