Controlled Oriented Attachment of Bipyramidal-Shaped Anatase TiO₂ and Their Enhanced Performance in Dye-Sensitized...

A low-cost hydrothermal method was used to synthesize high-purity bipyramidal single-crystals of TiO₂ enclosed with high percentage of (101) facets. The oriented attachment behavior can be controlled by fine tuning the reaction temperature. This played an important role in determining the crystal growth along [001] direction resulting in the self-assembly of the bipyramid crystals into connected ones to form single-crystal nanrods without the loss of surface area. In addition, the relationship between oriented attachment and the photovoltaic performance of such anatase TiO₂ nanocrystals in photoanodes of DSCs was investigated. The highly oriented sample reached a maximum overall energy conversion efficiency of 8.63 %. These results further illustrated that the highly oriented samples have superior charge transport ability derived from the enhanced long-range atomic arrangement with reduced grain boundaries and comparable uptake of dye molecules.