Hydrothermal synthesis of size- and shape-controlled CaTiO3 fine particles and their photocatalytic activity

Calcium titanate fine particles controlled precisely in size and morphology were synthesized by an optimized hydrothermal method. Their photocatalytic activity was evaluated as the effect of the particle morphology, that is, the exposed surface. The size and morphology were successfully controlled with aging temperature and alternative use of Ti-sources, such as a TiO2 dispersion and titanium-triethanolamine complex. The photocatalytic activity of the CaTiO3 fine particles was measured by the evolution amount of H-2 from a methanolic aqueous solution and the decomposition of acetic acid in water. As a result, rod-like particles showed the highest photocatalytic activity for H-2 evolution. On the other hand, cubic-shaped particles exhibited a higher activity for the decomposition of acetic acid. Judging from electron diffraction images, both the cubic and rod-like particles were bound by {110} and {001} facets, but the rate of the {110} faces of the rod-like particles was much more than that of the cubic ones. The proper selection of the particle shape, outer surface is one of the key factors for the photocatalytic activity.