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.

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.

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.

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.