The role of NiO doping in reducing the impact of humidity on the performance of SnO2-based gas sensors: Synthesis strategies, and phenomenological and spectroscopic studies

Hae Ryong Kim, Alexander Haensch, Il Doo Kim, Nicolae Barsan, Udo Weimar, Jong Heun Lee

Research output: Contribution to journalArticlepeer-review

215 Citations (Scopus)

Abstract

The humidity dependence of the gas-sensing characteristics in SnO 2-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 0.64-1.27 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 SnO 2 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.

Original languageEnglish
Pages (from-to)4456-4463
Number of pages8
JournalAdvanced Functional Materials
Volume21
Issue number23
DOIs
Publication statusPublished - 2011 Dec 6

Keywords

  • NiO
  • SnO
  • gas sensors
  • humidity
  • response/recovery speed

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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