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.

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.

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.

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.