Ammonia sensor based on NASICON and Cr2O3 electrode

Abstract A compact tubular sensor based on NASICON (sodium super ionic conductor) and porous Cr 2 O 3 sensing electrode was designed for the detection of ammonia. The sensor gave excellent sensing properties to 50–500 ppm ammonia in air at 250–450 °C. The EMF value of the sensor was almost proportional to the logarithm of ammonia concentration, the sensitivity (slope) was −89 mV/decade at 350 °C. It was also seen that the sensor showed a good selectivity to ammonia, and an excellent resistance to water vapor. The sensor had speedy response kinetics to ammonia, the 90% response time to 50 ppm ammonia was 30 s, and the recovery time was 60 s.