CO, the product of incomplete combustion of carbon fuels and cracking reactions occur at high temperatures, oxidation reaction ect. has become one of the major sources of air pollution, which greatly threats human life and health and environmental protection. The body of CO maximum allowable limit is 10^-4, while in Europe the provisions of the environment CO must not exceed 10^-5. So, the detection and controlling of CO is becoming urgent, tungsten trioxide based gas sensor is considered to be the most promising sensor for detecting NO_x, O₂ and NH₃ and other poison gases, due to its simple structure, low cost, high sensitivity and gas sensing. This paper presents a method for preparing tungsten trioxide nanowire CO gas sensor which shows as follow:

 

1. Dissolve the weighed analytically pure sodium tungstate dihydrate (Na₂WO₄.2H₂O) in an appropriate amount of deionized water, and taken out ice water bath, magnetically stirred 0.5 to 1 hour;

2. Slowly add, dropwise, 3mol/L hydrochloric acid to the sodium tungstate solution until complete the reaction to generate a pale yellow precipitate tungstate micelle, then stir for 1 hour and centrifuge for 20 minutes;

3. Add an appropriate amount of deionized water and chemically pure potassium sulfate (K₂SO₄), then turns into a volume of 50 ml reaction vessel after stirring with a glass rod, remarks: the reaction vessel is suggested to be filled with a volume of 80%;

4. Sealed, and carried out hydrothermal reaction for 6 to 72 hours in the oven under 180~270°C, remove the reactor and cooled to room temperature until the end of the reaction; then repeatedly wash and filter the product with deionized water and absolute ethanol, finally get tungsten trioxide nanowire after dried;

5. Weighing and mixing sensitive material of trioxide nanowires, solvents of terpineol and ethanol and binder of ethyl cellulose by a certain proportion, and also an appropriate amount of a low temperature glass frit slurry is appreciate be added to enhance the adhesion with the substrate, magnetic stirring for 2 hour. Ultrasonic treatment for 1.5 hours and then stirred sufficiently to get sensitive magnetic slurry;

6. Using a screen printing method to print sensitive slurry on the silver electrode interdigital alumina substrate, after thermal heat treatment under 250 °C~ 450°C in the air for 1 hour, we finally obtain WO₃ nanowire CO gas sensor .