Axis-Oriented, Anatase TiO2 Single Crystals with Dominant {001} and {100} Facets

Owing to wide-ranging industrial applications and fundamental importance, tailored synthesis of well-faceted single crystals of anatase TiO2 with a high percentage of photoactive facets has attracted much research interest. In this work, single crystalline anatase TiO2 has been prepared using hydrothermal conditions with precursors such as TiF4 and TiCl3. Fluorine species (herein HF) are introduced as a stabilizing agent to reduce surface energies of anatase TiO2, especially {001} facets, which leads to a large percentage of the reactive {001} facets exposed in final assemblies or films of titania with the largest exposure area. Anatase TiO2 single crystals with various degrees of truncation are prepared as a result of differences in relative concentration ratios of HF to TiF4. The rice-like anatase single crystals with exposed {100} facets were prepared in the system using TiCl3 precursor. Carboxymethyl cellulose (CMC), used as a dispersing agent, helps to control the reaction rate and suppress the agglomeration of truncated and rice-like crystals. The effects of fluorine species and precursors on the quality, morphology, and crystal structure of anatase TiO2 single crystals have been investigated.