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

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 Pd_0.05-SrFeO₃ sensing electrode showed the highest sensitivity toward 1-30 ppm SO₂ at 575 °C, and exhibited a piecewise linear relationship between ΔV 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 Pd_0.05-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. [ABSTRACT FROM AUTHOR]