Sensing characteristics and mechanism of hydrogen sulfide sensor using stabilized zirconia and oxide sensing electrode

A new type of electrochemical sensors for H2S was developed by combining a Y2O3-stabilized zirconia (YSZ) tube with a sensing oxide layer of WO3. The sensor device composed was an electrochemical cell of the form, air, Pt/YSZ/WO3, Pt, H2S (+air). This device was found to respond well to 0.2-25 ppm H2S in air at 400 degrees C, with acceptable response rates. The EMF of the sensor was linearly related to the logarithm of the H2S concentration with a slope of -74 mV/decade. In addition, the EMF was hardly affected by the coexistence of CO2 and water vapor. Based on the measurements of anodic and cathodic polarization curves, the H2S sensing signal was suggested to reflect the mixed potential at the zirconia/WO3 interface. The possibility of amperometric detection by using the present device was also suggested.