Nano grain size tungsten trioxide may be used for the preparation of near-infrared shielding material, which mainly reflects its photochromic property. While tungsten trioxide also has electrochromic property.
For example, a uniform and dense nano-Ag film may be prepared by vacuum coating, and then a layer of tungsten trioxide may be deposited thereon by electrochemical method to prepare a nano-Ag/WO3 composite film.
The ultraviolet-visible absorption spectrum of the composite film when different voltages are applied in the electrolyte solution shows that the film is colorless at a voltage of 0.8V, and the film changes from the de-doped state to the doped state as the potential is gradually decreased. When it is reduced to -1.0V, its color changes to dark blue. The color can be inverted to colorless when the voltage is increased to 0.8V. In addition, compared with tungsten trioxide film, the composite film has a shorter response time, greater optical contrast and better stability.
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