Tungsten Oxide Sensor Metal Activation

Adding metal elements to the tungsten oxide sensor can significantly improve the sensor response characteristics and reduce the sensor operating temperature. Metal catalysts such as iron and titanium can increase the surface reaction sites of tungsten oxide sensors. However, precious metal catalysts such as silver and platinum can not only provide surface active sites, but also can change the electron concentration of the conduction band of the tungsten oxide sensor by doping, thereby improving the characteristics of the tungsten oxide sensor.

Silver can improve the response characteristics of the tungsten oxide sensor to nitrogen dioxide and lower its operating temperature. Silver was doped with tungsten oxide by a colloidal chemical method and it was found that the silver-doped tungsten oxide gas sensing layer showed high sensitivity to nitrogen dioxide at 150°C. And has good selectivity for hydrogen sulfide, ethanol, ammonia, acetone and other gases. However, there are still sensor heating problems at 150°C.

By synthesizing silver-containing tungsten oxide nanowires on porous silicon, a sensor responsive to nitrogen dioxide at room temperature was obtained. Experiments show that the gas sensitivity of sputtering 1 nm thick silver is best. When nitrogen dioxide was detected at room temperature, the sensitivity was 3.357. And it shows good performance for ammonia, alcohol and other gases.

Palladium is another noble metal, and its doping can also reduce the detection temperature. The sensor operating temperature is reduced by simply compounding palladium and tungsten oxide. A sensor for detecting hydrogen gas at 80° C. was prepared by synthesizing a palladium layer, a tungsten oxide nano-layer, and an electrode layer. By changing the electrode type, the thickness of the palladium layer and the thickness of the tungsten oxide layer affecting the sensor performance, optimal 2.5 nm palladium and 11.2 nm tungsten oxide were obtained. At 80°C, the sensor has a sensitivity of 4.77, a response time of less than 1 s, and a recovery time of 47 s.

• < Prev
• Next >