Water pre-adsorption effect on room temperature SnO2 nanobelt ethanol sensitivity in oxygen-deficient conditions
✍ Scribed by M. Li; L.J. Qiao; W.Y. Chu; Alex A. Volinsky
- Book ID
- 104092974
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 746 KB
- Volume
- 158
- Category
- Article
- ISSN
- 0925-4005
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✦ Synopsis
The water adsorption effects on room temperature ethanol sensitivity of a SnO 2 single crystal nanobelt was studied. SnO 2 nanobelt showed better electrical conductivity in air than in vacuum. The current increased linearly with relative humidity in air and with water concentration in vacuum. In the presence of water vapor, the SnO 2 nanobelt electrical response was quite different, depending on the H 2 O and C 2 H 5 OH molecules adsorption sequence. The current response to ethanol gas increased substantially when water was pre-adsorbed. However, no change was found without water pre-adsorbtion. This interesting behavior is ascribed to competition between the H 2 O and C 2 H 5 OH molecules trying to adsorb on oxygen sites at the tin oxide surface. Dissociated water acts as the surface conduction channel resulting in better conductivity, while ethanol is physisorbed without water pre-adsorption. Based on this sensing mechanism, SnO 2 nanobelt can be used as a highly efficient ethanol detector in humid air.