Fabrication, characterization, and photocatalytic properties of anatase TiO2 nanoplates with exposed {001} facets

Anatase TiO2 nanoplates, with average side length ranging from 90 to 200 nm and average thickness ranging from 20 to 60 nm, were successfully fabricated by annealing anodized TiO2 nanotubes with different heating rates. The as-synthesized TiO2 nanoplates and nanotubes were analyzed by field-emission scanning electron microscopy, X-ray diffraction, X-ray fluorescence spectroscopy, and transmission electron microscopy. To investigate the growth mechanism of the TiO2 nanoplates dominated by highly reactive {001} facets, different heating rates were applied appropriately during the thermal treatment. The results revealed that the heating rate during thermal treatment is critical in determining the nanostructure of anatase TiO2. The fast heating rate (samples were annealed when the temperature heated up to 450 °C) and the brittle property are the main reasons for the collapse of the anodized TiO2 nanotubes. The nanosized TiO2 species grow into TiO2 nanoplates with the exposed 60 % of {001} facets because the fluorated surface of TiO2 species can direct the formation of TiO2 nanoplates with exposed {001} facets. The photoactivity of the TiO2 nanoplates is higher than that of TiO2 nanotubes.