Tungsten trioxide is an indirect band gap n-type semiconductor metal oxide, which has broad application prospects in electrochromism, semiconductor, gas sensors and photocatalysis. Nano-sized tungsten trioxide has excellent properties. It has strong absorption for electromagnetic waves, which makes it to be solar energy absorbing material and military stealth material. The huge specific surface area and surface effect make it a kind of excellent catalyst. In addition, as a transition metal compound, it also possesses semiconductor properties and is a sensing material with great potential.

In the existing tungsten metallurgy system, since the industrial crude sodium tungstate solution contains various impurity elements and must be removed by various steps of removal, the entire process is time-consuming and energy-consuming, and creates some environmental issues. Among them, the process of removing Na is the most cumbersome, and it is unavoidable to increase mid-products of ammonium tungstate and APT.

Tungsten trioxide is an n-type semiconductor material with a narrow band gap (2.4-2.8 eV), is capable of responding to visible light, and has similar characteristics to TiO2 photocatalyst, which is stable, non-toxic, photo-resistant, and low-cost. Its valence band has a high potential and the photo-generated electron hole has strong oxidation ability.

Tungsten oxide is a transition metal oxide n-type semiconductor. As a functional material, in recent years, a large number of studies have found that tungsten-based oxides does not only can be applied as catalysis, electrochromism, battery electrodes, solar absorbing materials and invisible materials, but also has the semiconductor characteristics of heat-sensitive, pressure-sensitive and gas-sensitive.

Photocatalysis is a main measure to control environmental pollution in the future. Since the first use of titanium dioxide photocatalyst by the Japanese in 1972, the field of photocatalysis has experienced nearly half a century of development. At present, photocatalyst materials can be used in various fields and can be used for sewage treatment, air treatment, home environment purification, and even power generation.

Near-infrared light accounts for about 46% of the solar spectrum. In many countries, building energy consumption accounts for about 30-40% of national energy consumption, while energy consumed through glass doors and windows accounts for over 50% of building energy consumption. Building window glass energy-saving and insulation is of great significance for energy saving and emission reduction. Therefore, the development of thermal insulation coatings, especially architectural thermal insulation coatings closely related to human life, and has great practical significance.

The ethanol gas sensor can detect the ethanol content in drunk driving inspection or industrial production, So as to reduce or avoid traffic accidents or production safety accidents. In recent years, the development of ethanol sensors has become more extensive and in-depth, and the ethanol sensing characteristics of tungsten oxide have received extensive attention from researchers.