Electrochemical NOx Sensors for Emission Control of Automotive Exhaust Gas 2001-01-3281
Electrochemical NOx sensors for emission control of automotive exhaust gas were prepared coupling pellets of yttria-stabilized zirconia (YSZ), an oxygen ion conductor, with thick films of a semiconducting oxide (WO3) as an auxiliary phase. The obtained sensors were wholly exposed to the same atmosphere. Electromotive force (EMF), polarization curves and amperometric measurements were performed in air and at different concentrations of NO2 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 NO2 did not affect the bulk but only the electrolyte/electrode interface.