YSZ-Based Mixed Potential Type Sensors Utilizing Pd-doped SrFeO3 Perovskite Sensing Electrode to Monitor Sulfur Dioxide Emission

Abstract

Sulfur dioxide (SO2) is one of the key pollutants in the atmosphere that should be monitored in many combustion facilities. In this paper, YSZ-based mixed potential SO2 sensors were developed utilizing the perovskite-type SrFeO3 sensing electrode, and Pd doping was applied to enhance the sensing performance. It was found that the sensor utilizing the Pd0.05-SrFeO3 sensing electrode showed the highest sensitivity toward 1–30 ppm SO2 at 575 ° C , and exhibited a piecewise linear relationship between Δ V and the logarithm of SO2 concentrations in this concentration range. The significant enhancement of sensing performances by 5 at% Pd doping was mainly attributed to the increasing of electrochemical catalytic activity of the anodic reaction. After the sensing performance test in the temperature range between 525 ° C –625 ° C , 575 ° C was selected as the optimum operating temperature. The sensing performances of the developed Pd0.05-SrFeO3 sensor were further evaluated at 575 ° C , exhibiting good selectivity to CO, CO2, NO, and NO2 interference and good long-term stability. In addition, the fluctuation of oxygen concentration can be corrected by the Butler-Volmer equation following the mixed potential theory.