Oxygen-deficient Tungsten Oxide

As an important semiconductor material, tungsten oxide has been widely applied to gas sensing, photocatalysis, electrochromic and field emission due to its special defect structure and chemical properties. There are some non-stoichiometric proportions of tungsten oxide in the actual preparation.

Tungsten oxide is a common semiconductor photocatalytic degradation material. It is insoluble in water, non-toxic and harmless, has lower valence band band, variable band gap, and has photocatalytic effect under the irradiation of near ultraviolet light and part of visible light. However, only 6% of UV light and 40% of visible light are radiated to the ground, while the remaining IR area has a low utilization rate. Although it is possible to get the light source needed by adjusting the spectral range of an artificial light source, it consumes a lot of energy and outweighs the loss.

Due to the existence of a certain amount of oxygen vacancy defects in its crystal, it can improve the electrical conductivity to a certain extent and reduce the bandgap. Enhance the surface of tungsten oxide adsorption of substances, to provide more active sites for the catalytic reaction. So, in photocatalyst and electrode material has important research and application value.

Oxygen defects can improve the energy band structure of tungsten oxide, tungsten oxide valence band position increases, reducing the band gap, which can broaden the light response range. Therefore, oxygen-deficient tungsten oxide nanomaterials can be synthesized by controlling the gas atmosphere, temperature and pressure in the vacuum thermal oxidation process.

Tungsten oxide materials with surface oxygen deficiency can even be prepared by controlling their anoxic conditions after high temperature deoxidation. Surface oxygen defects will provide more oxygen to the center of adsorption. When oxygen molecules are chemically adsorbed by surface oxygen defects, oxygen molecules are deprived of electrons to form strongly oxidizing dioxygen ions that can oxidize organic molecules adsorbed around the tungsten oxide.

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