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 (Theta) response. The La0.8Sr0.2Fe0.95Pd0.05O3-delta particles with nano-structure 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 vertical bar Z vertical bar or Theta extracted from the impedance spectroscopy as the sensing signal, respectively. The results shows that the Theta response can provide higher sensitivity, shorter response time and better stability compared to the vertical bar Z vertical bar response for the same sensor, especially at high frequency and temperature. Compared with the sensor with La0.8Sr0.2FeO3-delta 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-delta sensing electrode to linear relationship for La(0.8)Sr(0.2)Fe(0.95)Pd(0.05)O(3-delta)sensing electrode. Meanwhile, the sensor with LSFP-SE also exhibits the enhanced stability and anti-interference ability to various coexistence gases. (c) 2018 Elsevier Ltd. All rights reserved.