Rod-shaped Tungsten Trioxide Nano Gas Sensitive Material

Gas-sensitive materials refer to a class of gas-sensitive materials. Usually, the resistance of these materials varies with the surrounding gas environment. Using the so-called selectivity and sensitivity, it can not only distinguish different kinds of gases, but also identify the concentration of specific gases. At present, the sensitive components made of gas-sensitive materials have entered the practical stage in the petroleum, chemical industry, coal mine, automobile manufacturing, electronics, power generation and other industrial departments, as well as environmental monitoring, residential harmful gas alarm, national defense and other departments.

Tungsten trioxide is a typical n-type semiconductor material. It has become a good conductive gas sensor material due to the interaction between the electronic conductance in vivo and the chemical adsorption on the surface of the material. In order to improve the gas sensitivity of tungsten trioxide, some scholars have developed a rod-shaped tungsten trioxide nano gas sensitive material, which is highly sensitive to VOC. It needs to be prepared by the following steps:

(1)When hydrogen peroxide is added to tungsten powder, the molar ratio of hydrogen peroxide to tungsten powder is (1.2-2): 1. The suspension is stirred and centrifuged to obtain tungstic acid solution.

(2)To the tungstic acid solution prepared by step (1) adding 0.9-1.1 times volume of anhydrous ethanol and glacial acetic acid mixed solution, the volume ratio of anhydrous ethanol and glacial acetic acid in the mixed solution is (0.8-1.2):1; stationary to obtain colloidal solution;

(3) The colloidal solution prepared by step (2) was dried to obtain dry gel, and then heat-treated at 350-550 ℃ for 1-2 h to obtain tungsten trioxide powder.

In the above process, the rod-shaped tungsten trioxide nano gas sensitive material was prepared by mixed heat treatment of tungsten trioxide and bismuth trioxide. Bismuth trioxide was added as liquid phase medium for tungsten trioxide orientation growth in subsequent heat treatment. On the other hand, due to the strong volatility of Bismuth trioxide during high temperature heat treatment, it was found that Bismuth trioxide was volatile in this process by energy spectrum analysis. Bismuth trioxide almost evaporates completely, which ensures that rod-shaped tungsten trioxide nanomaterials with purity greater than 99.95% can be prepared. It has high chemical activity and good sensitivity to most volatile organic gases. The sensitivity coefficient to acetone is as high as 23.78.

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