Mixed potential type sensor using stabilized zirconia and ZnFe2O4 sensing electrode for NOx detection at high temperature

Electrochemical sensors using tubular yttria-stabilized zirconia (YSZ) and the spinel-type oxide sensing-electrode (SE) were fabricated and examined for NOx detection at high temperatures. For a mixed-potential type NOx sensor, ZnFe2O4 has been found to give the highest NOx sensitivity among the other spinel-type oxides tested and reported to date. The ZnFe2O4-attached device gave a linear correlation between emf and the logarithm of NO2 (NO) concentration from 50 to 436 ppm in the high temperature range 600–700 °C. The sensing mechanism of the sensor has been discussed on the basis of the gas adsorption–desorption behavior and the catalytic activity for the oxides examined.