Hydrothermal Synthesis of Tungsten Oxide Nanowires

Tungsten oxide is a kind of transition metal oxide, which belongs to n-type semiconductor. At present, a large number of researches have found that w-based oxides not only act as catalytic, electrochromic, solar energy absorbing and invisible materials, but also have the characteristics of semiconductor functional materials such as heat sensitive, pressure-sensitive and gas sensitive.

A method of large-scale preparation of tungsten oxide nanowire gas sensing materials in a wide range by hydrothermal synthesis is adopted, and then a preparation method of tungsten oxide nanowire sensor with high sensitivity, good repeatability and high stability for H₂, CO and NH₃ is provided. The main process is as follows:

(1) Preparation of gas sensitive material slurry
Taking the prepared tungsten oxide nanowires as the main material, ethyl cellulose and terpineol as the adhesive, and adding a proper amount of glass material to enhance the adhesion between the sensitive material and the alumina substrate, the sensitive material slurry is prepared after the materials are mixed in proportion and stirred evenly.

(2) Component sintering
The slurry prepared by the above (1) is screen printed on the alumina substrate with silver electrode and lead wire, fully dried in air at 80 ℃, sintered in a box furnace at 300-450 ℃ for 1-2 hours, and a tungsten oxide nanowire gas sensor assembly is prepared.

(3) Component aging
The gas sensing module sintered in (2) above is aged at 300 ℃ for 120 hours to make a tungsten oxide nanowire gas sensor.

In the sintering process of step (2), the heating rate is 3 ℃ / min, and the sensitive element is naturally reduced to room temperature after holding at the highest temperature for 1-2 hours.

The advantages and positive effects of hydrothermal method are as follows: the preparation method and steps are very simple, the raw materials are widely used, the process parameters are easy to control, the energy consumption of the whole preparation process is very small, the prepared tungsten oxide nanowires have large specific surface area and high thermal stability, and the nanowires have low concentration (1-100ppm) H₂, CO and NH₃ has high sensitivity, good repeatability and high stability.

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