Effect of electrode material and design on sensitivity and selectivity for high temperature impedancemetric NOx sensors Page: 4 of 38
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to Digital Library by the UNT Libraries Government Documents Department.
Solid-state electrochemical sensors using two different sensing electrode com-
positions, gold and strontium-doped lanthanum manganite (LSM), were
evaluated for gas phase sensing of NO, (NO and NO2) using an impedance-
metric technique. An asymmetric cell design utilizing porous YSZ electrolyte
exposed both electrodes to the test gas (i.e., no reference gas). Sensitivity
to less than 5 ppm NO and response/recovery times (10-90%) less than 10 s
were demonstrated. Using an LSM sensing electrode, virtual identical sen-
sitivity towards NO and NO2 was obtained, indicating that the equilibrium
gas concentration was measured by the sensing electrode. In contrast, for
cells employing a gold sensing electrode the NO, sensitivity varied depend-
ing on the cell design: increasing the amount of porous YSZ electrolyte on
the sensor surface produced higher NO2 sensitivity compared to NO. In or-
der to achieve comparable sensitivity for both NO and NO2, the cell with the
LSM sensing electrode required operation at a lower temperature (575 C)
than the cell with the gold sensing electrode (6500C). The role of surface
reactions are proposed to explain the differences in NO and NO2 selectivity
using the two different electrode materials.
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Woo, L Y; Glass, R S; Novak, R F & Visser, J H. Effect of electrode material and design on sensitivity and selectivity for high temperature impedancemetric NOx sensors, article, September 23, 2009; Livermore, California. (https://digital.library.unt.edu/ark:/67531/metadc934562/m1/4/: accessed April 19, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.