Preparation and characterization of tungsten-loaded titanium dioxide photocatalyst for enhanced dye degradation

Tungsten-loaded TiO2 photocatalyst has been successfully prepared and characterized. TEM analysis showed that the photocatalysts were nanosize with the tungsten species forming layers of coverage on the surface of TiO2, but not in clustered form. This was confirmed by XRD and FT-Raman analyses where tungsten species were well dispersed at lower loading (<6.5 mol%), but were in crystalline WO3 at higher loadings (>12 mol%). In addition, loading with tungsten could stabilize the anatase phase from transforming into inactive rutile phase and did not shift the optical absorption to the visible region as shown by DRUV-vis analysis. PZC value of TiO2 was found at 6.4, but the presence of tungsten at 6.5 mol% WO3, decreased the PZC value to 3. Tungsten-loaded TiO2 was superior to unmodified TiO2 with 2-fold increase in degradation rate of methylene blue, and equally effective for the degradation of different class of dyes such as methyl violet and methyl orange at 1 mol% WO3 loading.