At present, China's major cities are booming in the construction of rail transit projects. Because of its unparalleled advantages, shield method has been widely used in the construction of rail transit tunnels.

The photoelectrochemical cell (PEC), which decomposes water to produce hydrogen and converts solar energy into chemical energy, is considered to be one of the most important ways to obtain energy instead of fossil energy. It is an important research direction in this field to find and study potential semiconductor materials by various methods.

In recent years, the appearance of nano material artificial analogy peroxidase can effectively overcome the above shortcomings of natural enzyme, showing strong catalytic activity and specificity. The quantum size effect, small size effect, interface effect, surface effect and macro quantum tunneling effect of nano tungsten oxide make it have more advantages in optical, magnetic, catalytic and chemical activities. Based on the quantum effect, quantum dots have a wide range of applications in solar cells, light-emitting devices, optical biomarkers and other fields.

As the name implies, violet tungsten oxide refers to a kind of tungsten oxide with a violet color. It is one of the stable oxides of tungsten, together with WO₃, WO_2.90 and WO₂. Why violet tungsten oxide is violet. It is closely related to its light absorption property.