Investigation on acetone sensing properties and mechanism of p-type Cr₂WO₆ nanoparticles

In the present work, gas sensors based on Cr₂WO₆ nanoparticles were fabricated by a screen-printing technique, and the sensing properties were characterized with acetone and other typical reducing gases under both dry and humid air backgrounds. Interestingly, it was found that Cr₂WO₆ sensors showed a p-type conduction characteristic with a highly sensitive response to acetone vapor in a relatively low concentration. In the presence of humidity, resistances of Cr₂WO₆ sensors were significantly increased; nevertheless, sensor responses were obviously inhibited. In addition, the basic sensing mechanism of Cr₂WO₆ sensor was also investigated based on oxygen adsorption behavior and catalytic properties of Cr₂WO₆ surface. According to experimental results, it is proposed that the resistive responses of Cr₂WO₆ sensor to reducing gases were highly oxygen-dependent, indicating that the surface oxygen adsorption and reaction also played the basic role in the sensing process as that observed in typical n-type MOS sensors. Additionally, sensors also suffered from a high cross-sensitivity to water vapor due to the competition of chemisorption of water and oxygen on the surface of Cr₂WO₆.