Photocatalytic Activity of Hierarchical Flower-Like TiO2 Superstructures with Dominant {001} Facets

The fabrication of well defined hierarchical structures of anatase TiO2 with a high percentage of reactive facets is of great importance and challenging. Hierarchically Flower-like TiO2 superstructures (HFTS) self-assembled from anatase TiO2 nanosheets with exposed {001} facets (up to 87%) were synthesized by a simple alcohothermal strategy in a HF-H2O-C2H5OH mixed solution using titanate nanotubes as precursor. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N-2 adsorption-desorption isotherms. The photocatalytic activity was evaluated by the photocatalytic oxidation decomposition of acetone in air and methyl orange in aqueous solution under UV illumination. The photocatalytic activity of HFTS was much higher than that of commercial Degussa P25 and tabular-shaped anatase TiO2 obtained using pure water as the synthesis medium. The enhancement in photocatalytic activity was related to several factors, including the hierarchically porous structure, exposed {001} facets, and increased light harvesting ability. The HFTS was also of interest for use in solar cells, photocatalytic H(2)production, optoelectronic devices, sensors, and catalysis.