Fabrication, characterization, and photocatalytic properties of anatase TiO_2 nanoplates with exposed {001} facets

摘要

Anatase TiO_2 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 TiO_2 nanotubes with different heating rates. The as-synthesized TiO_2 nanoplates and nanotubes were analyzed by fieldemission scanning electron microscopy, X-ray diffraction, X-ray fluorescence spectroscopy, and transmission electron microscopy. To investigate the growth mechanism of the TiO_2 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 TiO_2. The fast heating rate (samples were annealed when the temperature heated up to 450℃) and the brittle property are the main reasons for the collapse of the anodized TiO_2 nanotubes. The nanosized TiO_2 species grow into TiO_2 nanoplates with the exposed 60 % of {001} facets because the fluorated surface of TiO_2 species can direct the formation of TiO_2 nanoplates with exposed {001} facets. The photoactivity of the TiO_2 nanoplates is higher than that of TiO_2 nanotubes.