YSZ/AG POTENTIOMETRIC SENSOR FOR REDUCING GAS-DETECTION

The response of a potentiometric YSZ/Ag device in reducing gas-oxygen mixtures has been studied in the temperature range of 473 to 723 K for applying this device to a reducing gas sensor. In Ar-O2 and Ar-CO2-O2 mixtures, the YSZ/Ag device worked ideally as an oxygen sensor above 620 K. On the other hand, in AT-CO-O2 and Ar-H-2-O2 mixtures, the device did not respond to the free oxygen obtainable at equilibrium; the e.m.f. of the device did not show A-type behavior near the equivalence points and related to P(CO)/P(O2) or P(H2)/P(o2) ratio. This device can be used as a reducing gas sensor, which detects 70 ppm CO or 300 ppm H-2 in air at an e.m.f. of 10 mV at 653 K. The sensibility of the device increased with decreasing temperature down to 573 K.