Tungsten Oxide Nanoparticle Gas Sensor

Tungsten oxide is a kind of N-type semiconductor material with wide band gap. It is widely used in the field of gas sensors and can be widely used in the detection of various toxic and harmful gases. However, like most metal oxide semiconductors, tungsten oxide operates at a higher temperature (above 200 ℃), which greatly increases the power consumption of the sensor. Therefore, reducing the working temperature of tungsten oxide gas sensing materials has become the focus of scientific and technological personnel.

With the advancement of materials science and the maturity of instrument manufacturing, many preparation methods have been used to synthesize nanomaterials with different morphologies. For example, some scholars have used solvothermal methods to prepare tungsten trioxide nanorod bundle structures on ceramic substrates. The invention solves the problems that the tungsten oxide gas sensor of the prior art has low sensitivity to nitrogen oxide gas and high working temperature. The preparation method of the tungsten oxide nanorod bundle structure gas sensing material comprises the following steps:

(1)Ceramic wafers were used as substrates, and the substrates were placed in acetone solvent and ethanol for 15-20 minutes to remove organic impurities on the surface. Subsequently, the ceramic substrate was washed in deionized water, washed and dried in absolute ethanol, and then placed in an infrared oven.

(2)Dispose tungsten hexachloride reaction solution, dissolve 1.19 g tungsten hexachloride in 60 ml absolute ethanol, stir magnetically until all dissolve to form yellow solution. After that, 5ml deionized water was added into the yellow solution to form a blue six tungsten chloride solution.

(3)The tungsten hexachloride solution prepared in step (2) was transferred to the reactor and sealed. Then the reactor was placed in a constant temperature drying box. Tungsten oxide nanorod bundles were synthesized on the surface of alumina substrate at 200 C. The reaction time was 5-11 H. After the reaction, the reactor was cooled to room temperature naturally.

(4)The solvothermal products in step (3) were separated by centrifugation, washed repeatedly with deionized water and absolute ethanol, and then dried for 8-10 hours in a vacuum drying chamber at 60-80 ℃.

(5)Tungsten oxide nanorod bundle-based sensitive material slurry was prepared by mixing the tungsten oxide nanorod bundle powder obtained in step (4) with anhydrous ethanol and terpineol with volume ratio of 1:2 and mixing with ultrasound for 2 hours.

(6)The tungsten oxide nanorod bundle-based sensitive material slurry described in step (5) is coated on the aluminium oxide substrate coated with interdigital electrodes. It was then heat treated in a muffle furnace at 300-400 ℃, holding time of 2 h and heating rate of 2-5 ℃/min to increase the crystallinity of tungsten oxide nanorod bundles.

Tungsten trioxide nanorod bundles were fabricated on ceramic substrates by solvothermal method, providing a nitrogen oxide gas sensor with high sensitivity, excellent stability and compatibility with microelectronic technology, which can work at low temperature. It is a method to fabricate tungsten oxide nanorod bundles with large specific surface area and surface activity. The gas sensor based on the tungsten oxide nanorod bundle structure can achieve high sensitivity and selectivity for sub-ppm to ppb nitrogen dioxide gas.

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