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.

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.

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.

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.