Impedancemetric NO2 sensor based on Pd doped perovskite oxide sensing electrode conjunction with phase angle response

A novel impedancemetric NO2 sensor was developed using the sensing electrode of Pd doped perovskite oxide conjunction with phase angle (Θ) response. The La0.8Sr0.2Fe0.95Pd0.05O3-δ particles with nanostructure were in-situ prepared in the porous skeleton of La9.95K0.05Si6O26.95 bilayer electrolyte by the simple impregnation method. The sensing performances of the NO2 sensor were investigated with the total impedance value |Z| or Θ extracted from the impedance spectroscopy as the sensing signal, respectively. The results shows that the Θ response can provide higher sensitivity, shorter response time and better stability compared to the |Z| response for the same sensor, especially at high frequency and temperature. Compared with the sensor with La0.8Sr0.2FeO3-δ sensing electrode, the Pd doping in the sensing electrode makes the sensitivity of the sensor be effectively improved. The response signals depend on NO2 concentrations from logarithmic relationship for La0.8Sr0.2FeO3-δ sensing electrode to linear relationship for La0.8Sr0.2Fe0.95Pd0.05O3-δsensing electrode. Meanwhile, the sensor with LSFP-SE also exhibits the enhanced stability and anti-interference ability to various coexistence gases.