A facile synthesis of hierarchical TiO2 for dye adsorption and photocatalysis

Hierarchical flower-like H2Ti5O11 center dot 3H(2)O assembled with radial nanowires was fabricated via a template-free solution-based reaction, and was converted to TiO2 with distinct phases and morphologies by the subsequent acid-treating or annealing. The HCl treatment achieved the controllable conversion from titanate nanowires to rutile nanorods by varying the temperature and acidity. When compared with the as-synthesized titanate nanowires and the thoroughly transformed rutile nanorods, their mixtures were found to exhibit the best dye adsorption ability towards rhodamine B and methylene blue in water. The H2Ti5O11 center dot 3H(2)O nanowires decomposed in sequence to anatase and rutile after a subsequent calcination in air, via an intermediate phase of H2Ti4O9 center dot H2O. The hierarchical structure could be retained up to 800 degrees C. When utilized as photocatalysts to degrade rhodamine B in water, the 550 degrees C-calcinated powder, with mixed phases of anatase, rutile, and srilankite, demonstrated the highest photocatalytic activity.