Different Crystalline Forms of Tungsten Trioxide Gas Sensitivity Competition
Tungsten trioxide (WO3) is a kind of transition metal oxides, it is not only a kind of N type semiconductor material, is also a kind of "d0" oxide, this dual identity so it has many characteristics.
The research shows that there is rod, plate and rod plate three kinds of nano tungsten oxide crystal, gas sensing properties of tungsten oxide with different crystal morphology is slightly different, some scholars use tungsten trioxide for four kinds of common harmful gases were tested and concluded.
(1) The best working temperature of WO3 sensor in ethanol, acetone, ammonia and formaldehyde is 350 ℃, 300 ℃, 325 ℃ and 250 ℃, respectively, and the sensitivity reaches the maximum at gas concentration of 1000 ppm. 21.29, 10.82, 24.32 and 9.68 respectively, and the lowest detection concentration of gas sensors for four gases are 100ppm, 50ppm, 25ppm and 100ppm, respectively.
(2) The best working temperature of nano-plate WO3 gas sensor is 350 ℃, 300 ℃, 325 ℃ and 250 ℃, respectively, and the sensitivity reaches the maximum when the gas concentration is 1000 ppm, which are respectively 25.4 and 18.52 , 30.29 and 18.31, respectively, the sensitivity value of ammonia is up to 30.29; The minimum detectable concentration of nano-plate tungsten trioxide gas sensor for the four gases is 50 ppm, 50 ppm, 25 ppm and 100 ppm, respectively, of which the sensitivity is 2.81 when the ammonia gas concentration is 25 ppm, indicating that the nano- Tungsten trioxide gas sensor is very sensitive to low concentration of ammonia.
(3) Nanoplate rod-shaped tungsten trioxide gas sensor The best working temperature of the four gases was 350 ℃, 300 ℃, 300 ℃ and 250 ℃, respectively, and the sensitivity reached the maximum when the gas concentration was 1000 ppm, the minimum detection concentrations for the four gases at 9.11, 8.73, 14.23 and 6.89 gas sensors were 200 ppm, 50 ppm, 50 ppm and 100 ppm, respectively.
Gas-sensitive test results show that the three kinds of crystal tungsten oxide have their own strengths. However, the overall comparison shows that the plate-shaped nano-tungsten trioxide is slightly better than the other two types of tungsten trioxide in terms of the lowest detection concentration or sensitivity.
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