Study on the shape control and photocatalytic activity of high-energy anatase titania

In the present work, high-energy TiO2 photocatalysts with exposed {0 0 1} facets were tailored by hydrothermal reaction of tetrabutyl titanate (50 g) and HF solution at 200 degrees C for 24 h. The photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, nitrogen adsorption-desorption isotherms and X-ray photoelectron spectroscopy. The photocatalytic activity of the photocatalyst was evaluated by a photoluminescence technique using coumarin as a probe molecule. It shows that, with increase in the amount of HF, the shape of TiO2 evolves from octahedral bipyramid to nanosheet and the percentage of exposed high-energy {0 0 1} facets increases. The photocatalytic activity of the as-prepared high-energy anatase nanocrystals is positively related to the percentage of exposed {0 0 1} facets. When the amount of HF is more than 12 mL, the photocatalytic activity of anatase TiO2 nanosheets is high than that of P25. The high photocatalytic activity of the high-energy anatase TiO2 nanocrystals is ascribed to the synergetic effect of exposed high reactive {0 0 1} facets and surface fluorination. However, high concentrated HF (20 mL) results in the formation of cubic TiOF2, which shows very poor photocatalytic activity. (C) 2010 Elsevier B.V. All rights reserved.