Hydrothermal Synthesis of Tungsten Oxide Nanowires

Tungsten oxide is a kind of transition metal oxide, which belongs to n-type semiconductor and has a wide range of applications. At present, a large number of studies have found that tungsten-based oxides not only act as catalysts, electrochromic, solar energy absorption materials and invisible materials, but also have the characteristics of semiconductor functional materials such as thermal, pressure and gas sensitivity.

A hydrothermal synthesis method was used to prepare tungsten oxide nanowire gas sensitive materials in a wide range. A preparation method of tungsten oxide nanowire sensor with high sensitivity, good repeatability and high stability for H₂, CO and NH₃ was provided. The main processes are as follows:

(1) Preparation of Gas Sensitive Material Slurry
The tungsten oxide nanowires prepared above are used as main materials, ethyl cellulose and terpineol as binders, and glass materials are added to enhance the adhesion between sensitive materials and alumina substrates. The slurry of sensitive materials is prepared by mixing the above materials proportionally and stirring evenly.

(2) Component sintering
The slurry screen prepared above (1) is printed on the alumina substrate with silver electrodes and lead wires, fully dried at 80 ~℃ in air, and sintered in a box furnace at 300~450 ~℃ for 1~2 hours to prepare the tungsten oxide nanowire gas sensor module.

(3) Component aging
A tungsten oxide nanowire gas sensor has been fabricated by aging the sintered gas sensor at 300 ℃ for 120 hours.

During the sintering process of step (2), the heating rate is 3 C/min, and after holding for 1-2 hours at the highest temperature, the sensor will naturally drop to room temperature.

The advantages and positive effects of the hydrothermal method are: the preparation method and the preparation steps are very simple, the preparation materials are extensive, the process parameters in the preparation process are easy to control, the energy consumption of the whole preparation process is very small, and the prepared tungsten oxide nanowires have large the specific surface area and high thermal stability, and the nanowires have high sensitivity, good repeatability and high stability to low concentrations (1 to 100 ppm) of H2, CO and NH3 in gas sensitive applications.

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