Original Paper

Ionics

, Volume 14, Issue 1, pp 15-25

Zirconia-based planar NO2 sensor using ultrathin NiO or laminated NiO–Au sensing electrode

  • Vladimir V. PlashnitsaAffiliated withArt, Science and Technology Center for Cooperative Research, Kyushu University
  • , Taro UedaAffiliated withInterdisciplinary Graduate School of Engineering Sciences, Kyushu University
  • , Perumal ElumalaiAffiliated withArt, Science and Technology Center for Cooperative Research, Kyushu University
  • , Toshikazu KawaguchiAffiliated withArt, Science and Technology Center for Cooperative Research, Kyushu University
  • , Norio MiuraAffiliated withArt, Science and Technology Center for Cooperative Research, Kyushu University Email author 

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Abstract

The nanostructured thin NiO films with the thicknesses of 30–180 nm were examined as a sensing electrode (SE) for the planar mixed-potential-type yttria-stabilized zirconia (YSZ)-based NO2 sensor. The sensing characteristics were examined in the temperature range of 600–800 °C under the wet condition (5 vol.% water vapor). Among the NiO-SEs tested, the 60 nm-thick NiO-SE sintered at 1,000 °C was found to give the highest NO2 sensitivity in the NO2 concentration range of 50–400 ppm accompanying with fast response/recovery at the operating temperatures of 600–700 °C. The high NO2 sensitivity was attributed to the high catalytic activity for both electrochemical reactions of O2 and NO2 at the interface of NiO-SE/YSZ. The ultrathin gold layer with the thickness of about 60 nm was additionally formed on the 60 nm-thick NiO-SE to fabricate the laminated-type (60 nm NiO/60 nm Au)-SE. It was demonstrated that the use of this laminated (NiO–Au)-SE improved both the sensitivity and the selectivity to NO2.

Keywords

NOx sensor Mixed potential Stabilized zirconia NiO Au Thin film