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

Bi 2 O 3 modified La 0.75 Sr 0.25 Cr 0.5 Fe 0.5 O 3-δ (LSCF) composites have been successfully prepared by self-demixing and used as the sensing electrode (SE) of an amperometric NO 2 sensor with yttria stabilized-zirconia (YSZ) electrolyte. The Bi 2 O 3 modified LSCF composites were formed from precursor La 0.75 Sr 0.25 Bi x Cr 0.5 Fe 0.5 O 3+δ (x = 0, 5%, 10%, 20%, 30% and 40%) after calcining at 1200 °C. The particle size of LSCF was increased with the Bi 2 O 3 content increasing. The YSZ porous framework structures were fabricated on YSZ to prolong TPB and the LSCF-xBi 2 O 3 -SE with porous structure was prepared on the porous YSZ backbone after calcining at 1000 °C. It is found that the sensors attached with LSCF-xBi 2 O 3 -SE are more sensitive to different concentrations of NO 2 (25–300 ppm) than the LSCF-based sensor. Among them, LSCF-20% Bi 2 O 3 based sensor exhibits the highest sensitivity (0.301 μA /ppm at 550 °C). The relationship between Δ I s and NO 2 concentrations of the sensor varies linearly at a given temperature. Meanwhile, the sensor shows well anti-interference capability for co-existent gases.