As an important functional material, tungsten trioxide has attracted much attention in research fields such as electrochromic devices, microsensors, surface acoustic wave devices, and microfluidic devices. And as an electrochromic device, tungsten trioxide has been more and more widely used in smart windows.

Hexagonal tungsten trioxide nanosheet film is a type of electrochromic film that can be prepared by hydrothermal method. In order to improve the electrochromism of tungsten trioxide, researchers usually construct a porous structural film using hexagonal phase tungsten trioxide of ions and electron conductivity, as the schematic illustration shown below.

Hydrated tungsten trioxide can be used to prepare electrochromic film as the hydrated WO3 tends to have a two-dimensional structure that provides additional permeation channels for ion transport and a high specific surface area. In addition, it is also because the crystal water in the hydrated WO3 can accelerate the ion transport efficiency, thus improving the electrochromic performance. Therefore, not only the tungsten trioxide of hexagonal phase, but also the hydrated tungsten trioxide attracts the attention of researchers.

Tungsten trioxide can be used to prepare functional film such as electrochromic films and the like. Recently, as electrochromic technology research has become hotter, the electrochromic film of tungsten trioxide nano particles has also become the focus of research. In addition, thin films of WO3 nano powder have received extensive attention in many applications such as sensors, photolysis of water, and solar cells.