Improvement of sensing performances of zirconia-based total NOx sensor by attachment of oxidation-catalyst electrode

The sensing performance of the mixed-potential-type total NOx sensor based on laminated yttria-stabilized zirconia (YSZ) sheets was improved by the attachment of oxidation-catalyst electrode. It was found that pure Pt was the best material for the catalyst electrode among the four Pt-based metals examined. The addition of 20 vol.% resin to Pt-electrode paste was quite effective to improve the catalytic activity of the electrode. The obtained sensor could measure total NOx concentration down to 10 ppm at 600 °C. The use of the oxidation-catalyst electrode was found to decrease largely the interference of reducing gases (C3H8 and CO) to the NOx sensitivity.