Application of advanced morphology Au-X (XÂ =Â YSZ, ZrO2) composites as sensing electrode for solid state mixed-potential exhaust NOx sensor

Among various NOx sensors developments, mixed potential sensor based on Yttria Stabilized Zirconia (YSZ) with a simple planar architecture Au/YSZ/Pt is of practical interest. Au composites electrodes were investigated to improve sensing performances. Such potentiometric solid-state gas sensors - were fabricated by screen-printing and tested for NO2 detection. Electrochemical impedance spectroscopy has shown that the addition of YSZ in the Au electrode decreased the polarization resistance in air. In addition, the (Au + 10 wt% YSZ)/YSZ/Pt sensor has a shorter response time and higher sensitivity to NO2 (range 20-100 ppm) at 450-550 °C in comparison with a reference Au/YSZ/Pt sensor. On the other hand, the addition of non-conductive ZrO2 does not significantly modify the electrochemical property but strongly damages the sensor responses toward NO2.