High sensitivity and selectivity of mixed potential sensor based on Pt/YSZ/SmFeO3 to NO2 gas

Yttria-stabilized zirconia (YSZ) ceramic has been well known as a solid electrolyte in electrochemical gas sensors working at high temperature. In this work, YSZ-8 (ZrO2 doped 8 mol% Y2O3) powder was synthesized by a sol–gel method. Crystalline structure of the synthesized powder YSZ-8 was analyzed by X-ray diffraction. The impedance spectroscopy investigation showed that the pressed plate YSZ-8 sintered at 1300 °C had good ionic conductivity at high working temperature. The gas sensing properties of the mixed potential sensor Pt/YSZ-8/SmFeO3 were investigated by exposing to NO2, CO, CH4, C3H8 and C6H14 at the operating temperatures from 300 to 500 °C. The experimental results indicated that the sensor Pt/YSZ-8/SmFeO3 presented very good sensitivity and selectivity to NO2 gas. The high sensitivity of the sensor Pt/YSZ-8/SmFeO3 to NO2 was suggested by relation to high catalytic activity of the oxide SmFeO3 to NO2.