Improvement of the response performance of impedimetric NO2 sensor by halogen doping of La0.75Sr0.25CrO3-δ sensing electrode

In this paper, the halogen doping in La0.75Sr0.25CrO3-δ (LSC) sensing electrode(SE) was proposed for improving the performance of the impedimetric NO2 sensor. The halogen doped LSC SEs were prepared by impregnation method and characterized by XRD, XPS, FESEM and EDS, respectively. The effects of halogen anion doping on the NO2 sensing performance of the sensors were investigated using alternating current impedance (AC impedance) measurement. Compared with Cl- and Br-, F- doping can significantly improve the sensing performances of the sensor to NO2 due to the improvement of the adsorption and electrochemical reduction reaction of NO2 on the SE. The sensor based on La0.75Sr0.25CrO2.95-δF0.05-SE (LSCF0.05-SE) exhibits the largest phase angle (Θ)response (18.08° for 700 ppm) and the highest sensitivity (12.51°/decade) at 450 ℃ among all sensors. In addition, the sensor has good stability, repeatability and anti-interference ability to CH4, CO2, NH3, H2 and NO.