期刊
ADVANCED FUNCTIONAL MATERIALS
卷 21, 期 23, 页码 4456-4463出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adfm.201101154
关键词
gas sensors; humidity; SnO2; NiO; response; recovery speed
类别
资金
- Korea Science and Engineering Foundation (KOSEF)
- Korean government [R0A-2008-000-20032-0]
- National Research Foundation of Korea [2008-0060083] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
The humidity dependence of the gas-sensing characteristics in SnO2-based sensors, one of the greatest obstacles in gas-sensor applications, is reduced to a negligible level by NiO doping. In a dry atmosphere, undoped hierarchical SnO2 nanostructures prepared by the self-assembly of crystalline nanosheets show a high CO response and a rapid response speed. However, the gas response, response/recovery speeds, and resistance in air are deteriorated or changed significantly in a humid atmosphere. When hierarchical SnO2 nanostructures are doped with 0.641.27 wt% NiO, all of the gas-sensing characteristics remain similar, even after changing the atmosphere from a dry to wet one. According to diffuse-reflectance Fourier transform IR measurements, it is found that the most of the water-driven species are predominantly absorbed not by the SnO2 but by the NiO, and thus the electrochemical interaction between the humidity and the SnO2 sensor surface is totally blocked. NiO-doped hierarchical SnO2 sensors exhibit an exceptionally fast response speed (1.6 s), a fast recovery speed (2.8 s) and a superior gas response (Ra/Rg = 2.8 at 50 ppm CO (Ra: resistance in air, Rg: resistance in gas)) even in a 25% r.h. atmosphere. The doping of hierarchical SnO2 nanostructures with NiO is a very-promising approach to reduce the dependence of the gas-sensing characteristics on humidity without sacrificing the high gas response, the ultrafast response and the ultrafast recovery.
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