Gas-sensitive materials refer to a class of gas-sensitive materials. Usually, the resistance of these materials varies with the surrounding gas environment. Using the so-called selectivity and sensitivity, it can not only distinguish different kinds of gases, but also identify the concentration of specific gases. At present, the sensitive components made of gas-sensitive materials have entered the practical stage in the petroleum, chemical industry, coal mine, automobile manufacturing, electronics, power generation and other industrial departments, as well as environmental monitoring, residential harmful gas alarm, national defense and other departments.

Semiconductor-catalyzed photocatalytic degradation of organic pollutants has become an ideal technology for environmental pollution control due to its unique properties such as complete mineralization of various organic pollutants and no secondary pollution by direct use of sunlight at room temperature. At present, photocatalytic semiconductors, such as titanium dioxide, SnO₂, CdS and ZnO, are widely studied and used.

The application of semiconductor photocatalyst in the degradation of toxic and harmful organic pollutants is of great significance for solving environmental pollution. However, broadband gap and low quantum efficiency are still the "bottlenecks" of photocatalysts. Therefore, the development of semiconductor heterojunctions is also an effective way to solve these problems, which can expand the spectral range of light absorption and inhibit the recombination of photoelectrons and holes.

Ammonium metatungstate is an important tungsten-containing compound. It is mainly used to produce various petrochemical catalysts and other tungsten compounds. It is the main raw material of tungsten-based catalysts in refineries. With the development of petroleum refining and petrochemical industries, the amount of ammonium metatungstate is increasing.

Tungsten trioxide is a stable n-type semiconductor material, which has been widely used in gas sensors and electrochemical catalysis. In recent years, some studies have applied tungsten trioxide to electrochemical energy storage. Studies have shown that tungsten trioxide and graphene aerogel composites can exhibit excellent capacitance performance.

Bearing, the important basic part of mechanical equipment, plays an important role in fixing and reducing the friction coefficient of load during the mechanical transmission. Tungsten disulfide coating is used in bearing processing to reduce the internal wear of the part.

Tungsten disulfide with lamellar structure is an excellent solid lubricant with good lubricant performance. It has many advantages in lubrication, so it is widely used in the fields of electronics, food, medicine, space machinery, etc.

Generally, tungsten disulfide can be prepared from tungsten trioxide, using it as the raw material. Tungsten disulfide with different purity can be prepared by this method according to different preparation conditions.

At present, tungsten oxide (WO₃) thin films with resistance sensitive layer are often used to monitor low concentration of NO₂ gas. The preparation methods of WO₃ thin films are to coat nano-tungsten oxide on planar interdigital electrodes or curved ceramic tube substrates by simple manual brushing or deposition. However, the specific surface area of tungsten oxide films prepared by this process is small, which restricts the improvement of the sensitivity of detecting nitrogen dioxide gas.

Tungsten oxide has outstanding electrochromic, photochromic, thermochromic and catalytic properties. It is confirmed that reducing the particle size of traditional electrode materials to zero dimension will greatly enhance the material and charge transport process, and it is expected to expand the application of quantum dots in the field of ultra-fast response electrochemical devices. Zero-dimensional tungsten oxide quantum dots can greatly improve the electroluminescent properties of tungsten oxide. The preparation process of tungsten oxide quantum dots includes the following steps: