Cadmium sulfide nanocrystals are the most widely studied and the most promising class of II-VI semiconductor nanocrystals. Due to their important nonlinear optical properties, luminescent properties and other physical and chemical properties, they have attracted worldwide attention. As a very important semiconductor material, it has been widely used in many fields, such as various light-emitting devices, laser and infrared detection devices, infrared windows and nonlinear optical materials and photosensitive sensors. Especially cadmium sulfide can absorb visible light very well, so it is the first choice material of photocatalyst.

In order to obtain a gas sensitive detector with high selectivity, high sensitivity, low working temperature and high stability, gas sensitive properties are mainly improved by modifying gas sensitive materials Tungsten oxide with one-dimensional nanowire structure attracts many researchers because of its huge specific surface area. In the aspect of gas sensing material modification, the main ways are doping noble metal Pt, Au, PD or transition metal oxide, in addition, it can be modified by constructing heterostructure. Compared with the two, the cost of heterostructure modification is relatively low.

Nano materials show a series of unique properties in micro scale, such as surface effect, quantum effect, small size effect, quantum tunneling effect and so on. Under the influence of these properties, nano materials, especially one-dimensional nano materials, show outstanding specific surface area, adsorption and desorption performance, which contributes to the development of one-dimensional materials.

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.

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.

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.

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.

Polluted wastewater and anti biotic wastewater are typical toxic and harmful industrial wastewater that are difficult to degrade, such as wastewater from pesticide industry and wastewater from some chemical industry. Because of the high concentration of fungicides in wastewater, which can kill and inhibit the growth of microorganisms, it is difficult to treat this kind of wastewater directly by biotechnology.

Tungsten is an irreplaceable key material in many fields due to its excellent high temperature resistance, high strength and hardness, especially in the fields of national defense industry and aerospace. Compared with the pure tungsten, the aluminum oxide coated tungsten and tungsten alloy can greatly increase the strength of tungsten, refine the grains, reduce the particle size, increase the toughness and tensile strength of the material.

Through a simple hydrothermal method, the researchers prepared a wide range of tungsten oxide nanowire gas sensing materials on a large scale, and then provided a tungsten oxide nanowire sensor with high sensitivity, good repeatability and high stability for H₂, CO and NH₃. The operation process is as follows: