Decomposition of Gas-Phase Organic Pollutants over Nanocrystalline Tungsten Oxide Photocatalysts under Visible-Light Irradiation

We have prepared visible-light-sensitive tungsten oxide (WO3) nanoparticle photocatalysts by a thermal plasma method and subsequent annealing treatment. The WO3 photocatalysts effectively decomposed acetaldehyde under visible-light irradiation and the activity increased with the annealing temperature. The WO3 annealed at 600 degrees C exhibited fivefold higher photocatalytic activity than nitrogen-doped TiO2 and commercial WO3. The high photocatalytic activity of the WO3 nanoparticles was attributed to their high crystallinity and large surface area. It was also found that the acetaldehyde decomposition rate over the WO3 nanoparticles was significantly enhanced by the addition of metal oxides such as ZrO2. The ZrO2 additive functions as an adsorbent of the acetic acid ( reaction intermediate) to remove the acetic acid from the WO3 surface. Furthermore, the complete oxidation of acetaldehyde into CO2 and H2O was achieved using a Ru (0.02 wt%)-loaded WO3-ZrO2 mixed oxide under visible-light irradiation, and this catalyst exhibited excellent durability for the reaction.