Sub-Stoichiometric Tungsten Oxide Preparation

In recent years, tungsten oxide materials containing oxygen defects have attracted the attention of researchers. Tungsten oxide lattice can withstand a considerable amount of oxygen vacancies, the performance of the unique non-stoichiometric. Oxygen vacancy in tungsten oxide can improve the conductivity and electrode activity of the material, and even a key factor in the electrode reaction. Oxygen vacancies in tungsten oxide as a shallow donor can improve its photocatalytic activity and electrochemical performance. Tungsten oxide exhibits better thermodynamic stability than other non-stoichiometric metal oxides, and oxygen vacancies can only occur in air at temperatures above 300 ° C.

Sub-stoichiometric preparation of tungsten oxide There are two main ways: First, direct synthesis, such as WO_2.72, WO_2.83, etc. can be directly synthesized. The second is the use of thermal injection method can be synthesized WO_2.83 nanowires. Aerobic defects exist in this structure. The sample is blue and has a distinct absorption peak at 900 nm in the near infrared. Showing an adjustable local surface plasmon resonance effect.

A second method for preparing sub-stoichiometric tungsten oxide is hydrogen reduction of tungsten oxide. Hydrogen was used to reduce tungsten oxide at high temperature and a disordered layer was obtained on the surface. The appearance of disordered regions provides more sites for trapping carriers, thus promoting charge transfer and catalytic activity. Since then, the research on hydrogen reduction of semiconductor materials has become a hot spot. Many researchers use this method to introduce oxygen vacancies in tungsten oxide to form oxygen-deficient tungsten oxide. The tungsten oxide is placed in a hydrogen atmosphere at high temperature annealing, the edge region becomes disorderly. At the same time, the formation of tungsten ions shows the existence of oxygen vacancies. And surface plasmon resonance appears, showing good optical properties.

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