YSZ-based solid electrolyte type sensor utilizing ZnMoO4 sensing electrode for fast detection of ppb-level H2S

The planar and compact type all-solid state electrochemical gas sensing device based on yttria-stabilized zirconia (YSZ) and Zinc molybdate (ZnMoO4) composite sensing electrode (SE) was proposed and fabricated to effectively detect ppb-level H2S at high temperature. The gas sensing property of different SEs (ZnMoO4, CoMoO4 and NiMoO4) is compared and explored. The sensor attached with ZnMoO4-SE processes the highest response value of - 62.5 mV to 1 ppm H2S and lower detection limit of 5 ppb H2S at 500 degrees C. The response and recovery times of the sensor to 500 ppb H2S are 20 s and 58 s, respectively. The sensor also displays high sensitivity, good continuous reproducibility, selectivity and stability of humidity and high temperature at 500 degrees C. In addition, the sensing principle involving mixed potential model was proposed and verified using polarization curves.