Defective Tungsten Oxide Nanomaterials

Unlike the stoichiometric tungsten oxide color, the defective tungsten oxide nanomaterials are light green or blue with an extra broadband absorption between 400 and 700 nm. This increased absorption peak is due to the presence of oxygen vacancies leading to a new band in the conduction band.

In fact, in addition to the electronic transition from the valence band to the conduction band, it also includes the absorption of a certain intensity of plasmon resonance corresponding to the energy band. Due to the very narrow bandgap, the defect tungsten oxide nanomaterials have become an n-type semiconductor photocatalytic material with potential for development, such as water oxidation, photocatalytic decomposition of water, carbon dioxide reduction and photodegradation of pollutants.

Because of its special crystal structure, the defective tungsten oxide nanomaterials have some unique properties such as increased conductivity, photochromes and near-infrared absorption. It can be applied to color-changing windows, photocatalysts, supercapacitors and gas sensors. The defect tungsten oxide nanomaterials have been explored and reported, and the surface clean ultrathin tungsten oxide nanowires have been synthesized by a simple one-step solvothermal method without surfactants or polymers as stabilizers. The catalytic effect of photocatalytic reduction of carbon dioxide on the defects of tungsten oxide nanowires under visible light conditions was tested. Defective tungsten oxide nanowires show higher catalytic activity without noble metal as catalyst.

The results show that because oxygen vacancies provide many reduction sites for the reduction reaction, carbon dioxide is converted into methane molecules. At the same time, the presence of oxygen vacancies can produce a "trap" effect, firmly "grab" carbon dioxide molecules, thereby enhancing the adsorption of carbon dioxide molecules. The first successful synthesis of morphologically low-cost non-stoichiometric defects of tungsten oxide nanomaterials. This non-stoichiometric defect tungsten oxide nanomaterial has a certain reduction ability. The precious metal particles are directly deposited on the surface of the defective tungsten oxide nanomaterial by utilizing the weak reducing ability of the low-cost tungsten oxide and the reaction of the noble metal salt solution by in-situ reduction.

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