When a semiconductor irradiates light with energy above bandgap, the electrons of valence band excite in the conduction band, generate holes in the valence band, and generate electrons in the conduction band. They have strong oxidation and reduction abilities respectively, and have redox effects on molecular species in contact with semiconductors. Such an action is called photocatalysis, and such semiconductors are called photocatalysts.

With the rapid development of economy, the demand for tungsten and cobalt in machinery manufacturing, geology, mining, construction, electronics and chemical industries is increasing. As rare metal elements, tungsten and cobalt are also the main raw materials of cemented carbide. Therefore, it is very meaningful to recycle tungsten and cobalt from scrap cemented carbide.

In the study of photocatalysis of bismuth tungstate, scholars believe that morphology control has always been a research hotspot in nanomaterials. As the simplest layered Aurivillius oxide, Bi₂WO₆ has a layered structure, which is most conducive to the formation of two-dimensional structure. The reaction conditions of synthesis can be controlled to obtain complex multi-level structure, so as to improve its photocatalytic performance. Therefore, a new preparation method upgraded to hydrothermal synthesis came into being, which is called microwave hydrothermal method.

With the shortage of fossil energy, rising oil prices and increasing environmental pollution caused by vehicle emissions, there is an urgent need to find new alternative energy sources. Among them, biodiesel has attracted people's attention because of its renewability and low emission.

Tungsten disulfide (WS₂）has the same structure as molybdenum disulfide. It is a typical sandwich layer structure. Due to its relatively weak van der Waals force between layers, it can also be stripped into single or few layers of nanosheets. It is considered to be another equivalent. An important two-dimensional nanosheet material with unique physical, chemical and electrical properties.

Tungsten carbide-based thermal spraying alloy material is one of the most widely used hard surface materials, and is also one of the strategic basic materials to support our modern industry and modern national defense. It is mainly WC-based composite powder or WC-based alloy powder formed by adding Co, Cr, Ni, Mo and other metals into tungsten carbide.

Tungsten carbide is one of the most important materials in transition metal carbides. It has excellent properties such as high melting point, hardness, thermal stability and mechanical stability. It is widely used in making cemented carbide materials and has important applications in cermet, mechanical processing, metallurgical minerals, aerospace and other fields.

Fuel cell is an electrochemical device that directly converts chemical energy into electrical energy. One of its key materials is electrode catalyst. For a long time, precious metals such as platinum and ruthenium have been widely used because of their excellent catalytic performance. Alloy catalyst can reduce the Pt loading and improve the catalytic efficiency, but the stability of catalyst needs to be improved.

Tungsten has the advantages of high melting point, high strength, high hardness and high wear resistance. In addition, it has low thermal expansion coefficient, good corrosion resistance and oxidation resistance, and good conductivity and thermal conductivity. Therefore, tungsten has been widely used in cutting-edge scientific fields, national defense industry and civil industry.

Phycocyanin is a fat-soluble natural carotenoid. Modern science finds that phycocyanin contains a special structure of propadiene and alkylene oxide. This special structure leads to many important physiological activities, such as anti-tumor. Activity, anti-obesity activity, antioxidant activity, regulation of blood sugar, scavenging free radicals, etc., have broad prospects for development in the fields of food, medicine, health care products, and beauty products.