Tungsten oxide film has important application value in display field because of its excellent electrochromic characteristics. It can effectively improve its electrochromic performance by doping a proper amount of FTO (fluorine doped tin oxide) nanocrystals. The display device prepared by the film has the characteristics of no blind angle, high contrast, low energy consumption, and can be used as electronic paper, indicator board, etc.

Electrochromism refers to the phenomenon that the optical properties (transmissivity, reflectance or absorptivity) of materials in the ultraviolet, visible or (and) near infrared region produce stable and reversible changes under the action of external electric field, which shows reversible changes of color and transparency in appearance.

In 1972, Honda and Fujishima successfully used n-TiO₂ electrode to produce hydrogen from water by photolysis of solar energy, which made people realize the application prospect of Photoelectrochemical conversion of solar energy to electric energy and chemical energy. At the same time, this technology is applied to solve the problem of dye wastewater and other industrial wastewater.

Bactericide wastewater is a typical kind of toxic and harmful industrial wastewater which is difficult to degrade, such as wastewater from pesticide industry and some chemical industry. Because of the high concentration of bactericide in wastewater, it can kill and inhibit the growth of microorganisms. On the other hand, most of the organic fungicides are polycyclic or heterocyclic organic compounds with poor biodegradability. Therefore, it is difficult to treat the bactericide wastewater directly by biotechnology.