Electrochemical NO_2 Sensors with WO_3 Electrodes for High Temperature Applications

摘要

Electrochemical NO_x sensors for high temperature applications were prepared coupling pellets of yttriastabilized zirconia (YSZ), an oxygen ion conductor, with a thick film of a semiconducting oxide (WO_3) as an auxiliary phase. The obtained sensors were exposed to the same atmosphere without the use of reference air. Electromotive force (EMF), polarization curves and amperometric measurements were performed in air and at different concentratins of NO_2 in air, at selected temperatures. Stable EMF values and fast response times were obtained. The sensors showed non-linear polarization curves. The role played by the electrolyte'electrode interface was determined by electrochemical impedance spectroscopy (EIS) tests: exposure to NO_2 did not affect the bulk but only the electrolyte/electrode interface.