Tungsten oxide powder is not only a transparent thermal insulation material, but a photocatalyst, which has good visible light absorption capability with a band gap of about 2.7eV. Generally, it is considered that the suitable photocatalyst has a band gap of 1.8eV.
In the study of the photocatalytic properties of tungsten trioxide, a more important research is using tungsten trioxide for photodecomposition of water to produce hydrogen. The conduction band and valence band positions of tungsten trioxide are around 0.7eV and 3.4eV, respectively. According to the theoretical calculations and experimental verification of the researchers, they believe that the photocatalyst may have photocatalytic performance in decomposition of water to produce hydrogen when the conduction band position of photocatalyst is higher than 0eV. And the photocatalyst may have photocatalytic performance in decomposition of water to produce oxygen when the valence band position of photocatalyst is lower than 1.23eV. Therefore, it can be concluded by comparing the above values that tungsten trioxide only has photocatalytic performance on hydrogen production.
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