In the field of energy, supercapacitor is a new type of energy storage device with rapid development in recent years. Its performance is between traditional capacitor and secondary battery. It has the characteristics of high power, fast charging and discharging rate, long cycle life, wide operating temperature range, good safety performance and economic and environmental protection. They are widely used.

Supercapacitors are energy storage devices between batteries and traditional capacitors. Because of its high charging and discharging efficiency, high power density, long cycle life and friendly environment, it is widely used in transportation, mobile communications, information technology, aviation, aerospace and national defense science and technology.

At present, the main friction materials are carbon fibers and carbon composites. Because the wear resistance of carbon composites is relatively low and easy to wet, people are looking for friction materials with higher wear resistance.

Since the first discovery of photocatalysis by Japanese scientists in 1972, photocatalysis has been applied in many fields, including water treatment, and its development prospects have been widely recognized. Tungsten trioxide is regarded as one of the most promising photocatalysts because of its visible light response. However, one of the difficult problems it faces is its poor catalytic activity. Therefore, it is still the focus of photocatalytic research to find a simple synthesis method, low cost and high photocatalytic activity of tungsten trioxide.

Photocatalysis is a technology that uses the light energy existing in nature to convert into the energy needed for chemical reaction to produce catalytic effect. By this way, it can decompose organic substances harmful to human body and environment without causing waste of resources and formation of additional pollution. A large number of studies have shown that almost all organic pollutants can be effectively photocatalytically degraded.

CaWO₄, PbWO4, NaBi(WO₄)₂ and CaMoO₄ crystals with scheelite structure (ABO₄) are better scintillators or X-ray emitters. The results show that the molybdate and tungstate with scheelite structure belong to tetragonal system, and their grains are tetragonal, biconical or plate-like. They are important photoelectric functional materials, scintillating materials and fluorescent materials.

Bismuth tungstate is a multi-functional material, which has physical and chemical properties such as piezoelectricity, ferroelectricity, pyroelectricity and catalysis. It has been widely used in ionic semiconductors, ferromagnetic materials, catalysis and many other fields. The band gap of Bi₂WO₆ is only about 2.75eV. This is because the valence band of Bi₂WO₆ is composed of Bi₆s and O₂ orbital hybridization, which increases the valence band potential of photocatalyst and effectively reduces the band gap of semiconductor. Therefore, Bi₂WO₆ is considered as one of the most promising visible light-responsive semiconductor photocatalysts.

Electrolysis is the cleanest way to produce hydrogen, but because it requires a lot of electricity and expensive catalysts (such as platinum), it is expensive. For this reason, most of the hydrogen produced by developed countries in the world is made from natural gas through a process called steam reforming. Although it is cheaper, it also produces greenhouse gas carbon dioxide. Moreover, China is not a big country with natural gas reserves. In addition, platinum metal is not only precious, but also produces toxic by-products. Therefore, searching for hydrogen evolution materials with low overpotential, low cost, high earth content and large-scale synthesis is the goal that scientists focus on.

In the diagnosis of kidney disease, it is necessary to detect ammonia gas by breath analysis. Now the ammonia gas sensor used in human exhaled gas analysis and detection technology needs to face the complex environment of low gas concentration, many kinds of interfering gases, high concentration and high humidity. This requires that ammonia gas sensor has high sensitivity and small size. Due to the characteristics of cheapness, cheapness and on-line measurement, the sensitive materials used in ammonia gas sensor also need to have the characteristics of high sensitivity, high selectivity, high stability, simple preparation and low cost.

Metallization modification of the welded surface of alumina composite single crystal is the precondition of reliable sealing with metal. Conventional molybdenum-manganese metallization process, sintering temperature is generally about 1400 ℃, later welding or use process exceed this temperature, the glass phase in the metallized layer will flow, destroy the metallized layer, thereby affecting the sealing strength and sealing gas tightness of ceramics-metal and other properties. Moreover, the low metallization sintering temperature also limits the selection of high temperature quinone solder for sealing alumina composite single crystal with metal, and directly limits the high temperature use of sealing parts.