Study of YSZ-based electrochemical sensors with oxide electrodes for high temperature applications

Potentiometric sensors based on yttria stabilized zirconia (YSZ) with WO3 as sensing electrode were fabricated using either Pt or Au electrodes. The sensors were studied in the temperature range 550-700°C in the presence of different concentrations (300-1000 ppm) of NO2 and CO in air. The response to NO2 was very stable with fast response time (20-40 s). The best sensitivity (18.8 mV/decade) using Pt electrodes was observed at 600°C. At the same temperature a cross-sensitivity (-15 mV/decade) to CO gas was also noticed. The response to CO was decreased (-4 mV/decade) using Au electrode. The role played by WO3 on the sensing electrode was discussed