Novel high-selectivity NO2 sensor incorporating mixed-oxide electrode

Solid-state planar sensor using scandia-stabilised zirconia (8mol% Sc2O3-ZrO2) solid electrolyte and CuO+CuCr2O4 mixed-oxide sensing electrode has been tested in NO2 containing gaseous atmosphere in the range of 10-500ppm NO2 between 518 and 659DDGC. The sensor has been found to respond consistently and rapidly to change in concentration of NO2 in the oxygen rich gas mixture at 659DDGC. At 659DDGC, a logarithmic relationship between the measured electromotive force (EMF) and NO2 concentration from 100 to 500ppm has been observed whereas a linear relationship between EMF and NO2 concentration has been observed below 30ppm. The sensor showed negligible cross-sensitivity to O2, CO and CH4 in the gas stream at 659DDGC. A possible sensing mechanism has been discussed.