Yellow tungsten oxide (WO3) is an n-type transition metal semiconductor, which can be used as a semiconductor gas sensor. WO3 has been considered as one of the most promising novel oxide gas sensing materials for the detection of NOx, SOx, NH3, CO, hydrogen and hydrogen sulfide and other gases. The principle of WO3 is that when it is exposed to the specific gas, oxygen is adsorbed from the air as an electron acceptor states in the band gap material of tungsten trioxide, surface reaction leading to the acceptor states in the portion of the surface coverage changes, causing the change of electrical conductivity, thus to realize detecting specific gas concentration.
There are many fruits about research of tungsten trioxide gas sensor, such as:
1. WO3 thin film gas sensor, which is depended on target of tungsten, and prepared by opposite target magnetron sputtering method on the substrate covered with interdigitated platinum electrode, and finally obtained after heat treatment;
2. WO3 hydrogen optical fiber sensor, which takes multi-mode silicon dioxide as the carrier, and tungsten is deposited on the fiber head by radio-frequency sputtering, then corroded into tungsten acid film, and then by controlling a certain calcination temperature to obtain yellow tungsten oxide hydrogen optical fiber sensor;
3. Porous silicon substrate WO3 nano-thin film gas sensor, which combines the advantages of porous silicon and WO3 to form a gas sensor with properties of low working temperature (room temperature) and high sensitivity;
4. Mesoporous WO3nanofibers with uniform distribution of Pt, Pd and Rh, which has a great potential in the diagnosis of disease reliability;
5. Tungsten trioxide nanowire CO gas sensor, which takes analysis of pure sodium tungstate dihydrate (Na2WO4.2H2O) as the raw material, adding potassium sulfate (K2SO4) to prepare the yellow tungsten nanowire, and then making the sensitive slurry coated on the interdigitated silver electrode alumina substrate, finally heat treatment to obtain.