Effect of Al 2 O 3 in Porous Zirconia Electrolytes for NO Sensing

Abstract

© The Author(s) 2016. Published by ECS. All rights reserved. The electrochemical behavior of NO sensors composed of a partially-stabilized Y 2 O 3 -ZrO 2 (PSZ) porous electrolyte with 0, 2, 3.8, 5 and 10 wt% Al 2 O 3 additions was investigated using the impedancemetric technique. The addition of Al 2 O 3 modified ionic transport within the electrolyte, and caused the electrode/electrolyte interfacial resistance to increase. NO sensors with a PSZ electrolyte containing 2 wt% Al 2 O 3 demonstrated greater sensitivity to NO under dry and humidified gas conditions, in comparison to the other composite PSZ-Al 2 O 3 based sensors. The 2 wt% Al 2 O 3 addition provided enhance grain boundary conductivity within the PSZ electrolyte, and possibly limited oxygen reactions along the triple phase boundary; thereby, enabling NO reactions to proceed more readily. Impedance spectroscopy measurements of the various PSZ-Al 2 O 3 based NO sensors were collected for different operating conditions in order to interpret the behavior of: 1) the electrical response, 2) interfacial NO reactions, and 3) the NO sensing response due to the addition of Al 2 O 3 .