Tungsten Oxide Photocatalyst Defects

Tungsten oxide is considered as one of the most promising photocatalysts because of its wide range of raw materials, low price, green pollution and stable optical properties. The tungsten oxide photocatalyst has been successfully used in the experiment of removing contaminated water and air pollutants. In addition, tungsten oxide has also been widely used in other fields, such as photocatalytic decomposition of water, photovoltaic equipment, carbon monoxide oxidation, carbon dioxide photoreduction, photoelectrochemical cells, photocatalytic degradation of dyes.

Although tungsten oxide has a wide range of applications, there are still some disadvantages of tungsten oxide in photocatalysis. Its defect is mainly due to the lower position of the conduction band of the tungsten oxide photocatalyst. This makes the photoproduced valence band produced by its valence band with higher oxidation ability inhibited in the photooxidation process. Secondly, for the application of tungsten oxide photocatalyst in photo electrochemistry, the tungsten oxide photocatalyst can only utilize 4-6% of the solar energy because its band gap of 2.6-2.7 eV limits the photoelectric conversion efficiency.

Due to the high photocatalytic charge recombination rate in tungsten trioxide, its quantum yield is low, which is also a factor restricting its practical application. Therefore, the tungsten oxide photocatalyst needs to be modified to improve its photocatalytic performance. However, at present, there is not a single solution to these problems at one time because many factors are contradictory. For example, for wide band gap semiconductor photocatalysts, although the use of a smaller spectral range, but it has a strong ability of photoreduction oxidation.

However, for the smaller bandgap semiconductor photocatalyst, although the available light is greatly increased, the decrease of the forbidden band width means that it has a lower photo-redox capacity. In addition, tungsten oxide itself also has some unique physicochemical properties. For example, tungsten oxide can exhibit different crystal structures at different temperatures, and different crystal structures have different physicochemical properties.

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