Solid-state NOx sensor combined with NASICON and Pb–Ru-based pyrochlore-type oxide electrode

Solid-state electrochemical sensor devices combined with sodium super ionic conductor (NASICON: Na1+xZr2SixP3−xO12) discs and Pb–Ru-based pyrochlore-type oxide electrodes have been developed for the detection of NO and NO2 in the range 10–1000 ppm at 400°C. Sensor devices fitted with pyrochlore-type oxide electrodes showed good EMF responses to the sample gases containing NO or NO2. EMFs were almost linear to the logarithm of NO or NO2 concentration, while the value and slope of the EMF responses were changed drastically, depending on the electrode materials. Among the devices tested, the one attached to Pb2Ru1.9V0.1O7−z electrode gave the best response performance to NO and NO2, i.e., the 90% response time to 500 ppm NO or 110 ppm NO2 was as short as 30s or 1 min, respectively.