High temperature potentiometric NO2 sensor with asymmetric sensing and reference Pt electrodes

The focus of this paper is on fabrication of planar potentiometric NO2 sensors with asymmetric reference and sensing electrodes, both made with Pt, and deposited on yttria-stabilized-zirconia electrolyte. Both electrodes were initially derived form Pt ink. Using a rapid electrochemical method based on surfactant-templated electrodeposition, highly porous Pt was deposited on one of these electrodes and it served as the reference electrode. The increased surface area of the reference electrode leads to asymmetry between the sensing and reference electrodes and the device performed well as a high temperature potentiometric NO2 sensor. These results also provide direct evidence of the role of non-electrochemical reactions, in this case the equilibration of NO/NO2 in design of sensors. The simplicity of the sensor design, its compactness, a 1-2 min electrodeposition process, and the use of only two materials (YSZ and Pt) are the attractive features of this device. (C) 2009 Elsevier B.V. All rights reserved.