CO sensing performances of YSZ-based sensor attached with sol-gel derived ZnO nanospheres

Zinc oxide nanospheres (ZnO) were synthesized by modified sol-gel route using zinc nitrate as precursor and citric acid as gelling agent. Yttria-stabilized zirconia (YSZ)-based sensor was fabricated using the sol-gel derived ZnO nanospheres as sensing electrode and Pt as reference electrode. The sensing characteristics were examined in the temperature range of 600-800 degrees C under various O-2 concentrations (5, 10, 15 and 21 vol.%). It turned out that the sensor attached with the sol-gel derived ZnO-SE exhibited selective and sensitive response to carbon monoxide (CO) at 700 degrees C in all measured O-2 concentrations. The sensor using sol-gel derived ZnO-SE showed high response and selectivity to CO at 700 degrees C in 5 vol.% O-2. The response of the sensor varied linearly with CO concentrations on the logarithmic scale. The sensing mechanism was confirmed to be mixed-potential type. The sensor retained good stability even for about 40 days. The nano features associated with the sol-gel derived ZnO led to high response and selectivity to CO.