Hydrothermal synthesis and photocatalytic activity of whisker-like rutile-type titanium dioxide

Nanowhiskers of rutile-type titanium dioxide (TiO₂) were synthesized by a simple hydrothermal treatment of a water-soluble titanium-glycolate complex at 473 K. The aspect ratio of the obtained rutile particles could be controlled by changing the concentration of the glycolic acid additive in the starting aqueous solution of the titanium complex. According to high-resolution transmission electron microscopy, whisker-like nanoparticles grow along the c-axis of rutile, the side facets of which are (110), (-110), (1-10), and (-1-10). Glycolic acid controls promotion of the rutile particles in the specified direction due to its preferred adsorption on the titanium-rich facets. Evaluation of the photocatalytic activity of the synthesized TiO ₂ was performed in terms of decomposition of oxalic acid in an aqueous system under ultraviolet irradiation. It turned out that this particular whisker-like shape is responsible for the tremendous enhancement of rutile photocatalytic activity, and even rutile samples with low surface area demonstrated photocatalytic performance comparable with one of the best nanosized anatase photocatalytic materials. Therefore, it can be concluded that the (110) rutile facet plays an important role in the photocatalytic oxidation reaction, and that it exhibits higher photocatalytic activity than the (001) facet in the decomposition of oxalic acid.