Amperometric SO2 gas sensors based on solid polymer electrolytes

Precious metals (Pt, Pd and Au) have been prepared on the solid polymer electrolyte (SPE) by chemical plating and vapor deposition. The characteristics of metal/SPE and the electro-oxidation behavior of sulfur dioxide on the prepared electrodes have been studied in this paper. A linear relationship between the limiting oxidation current and the concentration of SO2 was obtained. The sensitivities of the Pt/SPE, Au/SPE and Pd/SPE sensing electrodes were 2.26, 0.917 and 0.176 μA/(cm2 ppm), respectively, for SO2 concentrations in the range of 25–500 ppm. The effects of gaseous flow rate and the interference on the sensor performance were also studied.