Tungsten Oxide Structural Water Model

Structural water model of tungsten oxide produced by the hydrogen gas dehydrogenation of Pt catalyze the reaction of tungsten oxide and hydrogen on the surface of Pt: a part of hydrogen ions reacts with the oxygen ions on the surface of tungsten oxide to generate water molecules and release them from the film.

Another part of the hydrogen ions is injected into the tungsten oxide lattice to form structural water molecules with the oxygen atoms in the tungsten oxide lattice. The water molecules easily fall out of their original position under thermal disturbance or light irradiation, resulting in the occurrence of oxygen vacancies.

In the tungsten oxide structural water model, the valence state of tungsten ions changes from tungsten ions to tungsten ions due to the incoming electrons being filled into the conduction band due to the presence of oxygen vacancies. When Pt is surface-modified with tungsten oxide in oxygen or air, oxygen is changed to oxygen atoms at the Pt surface. Oxygen atoms capture the surface hydrogen ions to form hydroxide.

So that the carrier concentration in the nanorods decreases, causing the vacancy near the vacancy donor level electron state instability. When donor level electrons are trapped by oxygen vacancies on the surface of the nanorods, tungsten valences associated with oxygen vacancies will be caused to change from tungsten ions to tungsten ions

Pt surface modified tungsten oxide thin film has high sensitivity at room temperature, its working temperature up to 25 ℃. Operating temperature is lower than the traditional semiconductor hydrogen sensor operating temperature. The film has a hydrogen concentration detection range of 50 ppm-5000 ppm and a response time of less than 3 min. The resistance changes rate and hydrogen concentration into a linear relationship.

The detection range has reached the standard industrial hydrogen detection range, which can effectively reduce the operating temperature of the hydrogen sensor. It is confirmed that Pt surface modified tungsten oxide film has potential application in hydrogen sensor. According to the phenomenon found during the test of hydrogen gas sensor, the gas sensing mechanism of hydrogen and Pt surface-modified tungsten oxide film is explained by the surface potential barrier regulation and structure water model.

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