Supercapacitor is a new, efficient and practical energy storage device between battery and traditional capacitor. It has the advantages of fast charge-discharge speed, high power density, long service life, wide temperature window and friendly environment. In recent years, flexible supercapacitor has attracted more and more attention due to its unique advantages.

Bi₂WO₆, as a kind of p-type semiconductor material, has perovskite lamellar structure. Its band gap is about 2.7eV. Bi₂WO₆ has strong absorption in the visible region with wavelength greater than 420nm. It can use both ultraviolet and visible light in sunlight. It is more and more popular among researchers. However, due to poor adsorption, the separation efficiency of photogenerated carriers is low.

Semiconductor photocatalysts are highly praised for their stable physical and chemical properties, wide distribution on the earth, easy access, low cost and no secondary pollution. As a member of transition metal oxides, tungsten trioxide (WO₃) is an indirect bandgap n-type semiconductor material with a band gap of 2.2-2.8eV. It has good absorption of visible light, so it is a very promising semiconductor photocatalyst.

The application of semiconductor photocatalyst in the degradation of toxic and harmful organic pollutants is of great significance for solving environmental pollution. However, broadband gap and low quantum efficiency are still the "bottlenecks" of photocatalysts.