Amperometric type NO2 sensor based on La0.75Sr0.25Cr0.5Fe0.5O3-6-Bi2O3 sensing electrode prepared by self-demixing

Bi2O3 modified La0.75Sr0.25Cr0.5Fe0.5O3-6 (LSCF) composites have been successfully prepared by self-demixing and used as the sensing electrode (SE) of an amperometric NO2 sensor with yttria stabilized-zirconia (YSZ) electrolyte. The Bi2O3 modified LSCF composites were formed from precursor La0.75Sr0.25BixCr0.5Fe0.5O3+6 (x = 0, 5%, 10%, 20%, 30% and 40%) after calcining at 1200 degrees C. The particle size of LSCF was increased with the Bi2O3 content increasing. The YSZ porous framework structures were fabricated on YSZ to prolong TPB and the LSCF-xBi2O3-SE with porous structure was prepared on the porous YSZ backbone after calcining at 1000 degrees C. It is found that the sensors attached with LSCF-xBi2O3-SE are more sensitive to different concentrations of NO2 (25-300 ppm) than the LSCF-based sensor. Among them, LSCF-20% Bi2O3 based sensor exhibits the highest sensitivity (0.301 mu A /ppm at 550 degrees C). The relationship between Delta Is and NO2 concentrations of the sensor varies linearly at a given temperature. Meanwhile, the sensor shows well anti-interference capability for co-existent gases.