Titanium dioxide is known as a photocatalyst material, but it has little function in the absence of ultraviolet radiation. Therefore, Scientists prefer to study visible-light tungsten trioxide photocatalysts.

At present, most power plants in our country mainly use coal as fuel. The direct combustion of coal will produce a large number of nitrogen oxides which pollute the environment. At present, flue gas denitrification technology is widely used in developed countries to reduce the emission of nitrogen oxides, and the denitrification rate can reach more than 90%.

Energy shortage and environmental deterioration have become the most important problems facing all countries in the world. The development of new functional materials will be an effective way to solve these problems. Because of its unique physical and chemical and electronic properties, tungsten oxide materials have good application prospects in the fields of color-changing window, photocatalysis, fuel cell, chemical sensor, environmental purification, solar energy conversion and other functions, and have become one of the hot topics in the current research of new materials.

Recently, some scholars have attempted to prepare tungsten trioxide nanosheets with high specific surface area, high crystallinity, high dispersibility and low cost by mechanochemical method. The main process is to prepare tungstic acid (WO₃·H₂O) nanosheets using tungstic acid-based organic or inorganic layered hybrid micro/nanobelts (tubes) as precursors, and remove the organic matter between the precursor layers by nitric acid oxidation. The reaction temperature is 15-50 ℃. The time is 5-120 H. The tungsten oxide nanosheets are prepared by heating them at a heating rate of 1-5 ℃/min to 250-600 ℃, then holding them for 1-5 h, and then cooling them to room temperature naturally. The specific operation is as follows: