Nano Tungsten Oxide Nitrogen Dioxide Gas Sensing Film

At present, tungsten oxide (WO₃) thin films with resistance sensitive layer are often used to monitor low concentration of NO₂ gas. The preparation methods of WO₃ thin films are to coat nano-tungsten oxide on planar interdigital electrodes or curved ceramic tube substrates by simple manual brushing or deposition. However, the specific surface area of tungsten oxide films prepared by this process is small, which restricts the improvement of the sensitivity of detecting nitrogen dioxide gas.

In order to overcome the shortcomings of the existing technology, researchers have developed a gas sensing film based on nano-tungsten oxide. The preparation process of the nano tungsten oxide nitrogen dioxide gas sensing film is as follows:

Step 1, ammonium tungstate powder was mixed with water according to the weight ratio of 0.2:52, and stirred evenly to obtain ammonium tungstate precursor solution, in which water was deionized water, stirred by magnetic stirring for 1 minute.

Step 2: First, the monolayer colloidal crystal template is immersed in the solution of ammonium tungstate precursor. After it is separated from the substrate and floated on the surface of ammonium tungstate precursor solution, the monolayer colloidal crystal is picked up by the substrate and covered on the surface of the substrate to obtain a substrate coated with monolayer colloidal crystal and impregnated with ammonium tungstate precursor solution. Among them, the colloidal sphere used in the monolayer colloidal crystal template is polyphenyl. Ethylene colloidal sphere with ceramic tube as substrate. Substrates coated with single-layer colloidal crystals and impregnated with ammonium tungstate precursor solution were dried at room temperature and dried at 80 ℃ for 30 minutes, then gold films were modified by sputtering on the surface of the substrates, and the substrates coated with gold films and ammonium tungstate-impregnated single-layer colloidal crystals in turn were obtained. Substrates coated with gold film and ammonium tungstate impregnated single-layer colloidal crystals were annealed at 300 ℃ for 40 minutes. Substrates coated with gold film and bowl-shaped porous tungsten oxide film were obtained.

Step 3, repeat the process of step 2 to prepare nano tungsten oxide nitrogen dioxide gas sensing film.

The prepared nano-tungsten oxide nitrogen dioxide gas sensing film was used as the sensing element. The results showed that the target product exhibited higher detection sensitivity, faster response time and stronger selectivity for NO₂ gas through multiple batches of tests at the same concentration and temperature for NO₂, H₂S, C₂H₅OH, C₃H₆O, SO₂, H₂ and CH₄ respectively.

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