A comparative study on UV light activated porous TiO 2 and ZnO film sensors for gas sensing at room temperature

Abstract

In order to find a new approach for screening the photoactivated gas sensing materials with high sensitivity, a comparative study was carried out. With the simple technique of screen printing, TiO 2 and ZnO were used to fabricate the UV light activated gas sensors which were applied at room temperature. To facilitate the simultaneous measurements of the current transients of the two materials, they were printed on the same alumina substrate. Compared with ZnO, TiO 2 exhibited a superior performance to ethanol and formaldehyde gases. It was found that the responses of TiO 2 increased with the concentration of test gas and amounted to 224 and 1700 to 100 ppm ethanol and formaldehyde gases, respectively, while the responses of ZnO to 100 ppm ethanol and formaldehyde gases were 0.14 and 1.5, respectively. The mechanism of such a huge difference between TiO 2 and ZnO was discussed in detail. Furthermore, it is suggested that metal oxide semiconductor with lower photo-to-dark current ratio can achieve higher photoactivated gas sensitivity.