Preparation of Nanocrystalline W-doped TiO_2 Powders and Their Photocatalytic Properties under Visible Light Irradiation

摘要

Nanocrystalline W-doped TiO_2 powders with different initial W/Ti ratio in starting materials have been prepared by hydrothermal method. The phase composition, morphologies, specific surface areas and the photocatalytic activities under visible light irradiation of the synthesized powders have been characterized. XRD identification reveals that the synthesized powders were composed of anatase. No rutile has been detected in the products. The specific surface area of the powders was ranged from 185 to 210 m~2/g by BET measurement. The averaged grain size of the powders was calculated as about 12 run by Scheller's method. Uniform size distribution and good crystallinity have been confirmed by TEM. UV-Vis spectra show that the absorption edges of the synthesized W-doped TiO_2 powders with different nominal doping concentration of W ions have been red-shifted into visible light region, which suggests that the W ions have been doped into the lattice of TiO_2. In our case, W-doped TiO_2 with initial W/Ti atomic ratio of 1% in starting materials has the best photocatalytic activities when decompose the Methylblue in its aqueous solution, which is consistent with that of the theoretical results from our previous work.