As an important n-type semiconductor oxide, tungsten trioxide (WO₃) is widely used in chemical sensors, photocatalysis, energy conversion systems and other fields. Because of its large theoretical capacity (693 mAh/g), low cost and high safety (high melting temperature and mechanical stability), tungsten trioxide can also be used as negative electrode materials for lithium ion batteries.

At present, the existing processes for recovering and treating waste tungsten oxide to produce ammonium tungstate solution, ammonium paratungstate and ammonium metatungstate are all based on the chemical properties of all tungsten trioxide and blue tungsten oxide which are insoluble or slightly soluble in ammonia water and only soluble in caustic soda or soda ash. The process is to dissolve oxygen in normal pressure or pressure boiling with caustic soda (sodium hydroxide) solution or soda carbonate solution in advance. Tungsten carbide is prepared into sodium tungstate solution, or tungsten oxide is melted with sodium carbonate at high temperature, then tungsten is boiled and leached to form sodium tungstate solution.

Quantum dots (QDs) are a new kind of nano-fluorescent materials. Because of their unique electrical and optical properties, QDs have been widely used in physics, chemistry, biology and other fields. As a new fluorescent material.

Nitrogen oxide (NO_x), as a highly toxic gas, is the main source of acid rain and photochemical smog, which has posed a serious threat to human health and safety. Therefore, the detection of nitrogen oxides has become a research hotspot in recent years.