CO2 and SO2 tolerant Fe-doped metal oxides for solid state gas sensors

Perovskite-type BaMg0.33Nb0.34Fe0.33O3 − δ (BMNF) and double perovskite-type Ba2Ca0.66Nb0.68Fe0.66O6 − δ (BCNF) were prepared by conventional solid-state reaction at 1400 °C in air. Ex-situ powder X-ray diffraction (PXRD) and high temperature PXRD (30-700 °C) of BCNF and BMNF under CO2 and SO2 exhibited excellent chemical stability. Chemical stability under SO2 was further confirmed by scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX), where no sulfur-containing compounds were detected within the detection limit of the equipment. BCNF and BMNF were tested for their sensing properties in CO2 and SO2 at 500-700 °C by applying constant DC voltage (0.1 V). Ag and Pt current collectors were employed as electrodes for BCNF and showed similar response at 600 °C (t90 = 7 min) for ppm level of CO2 in dry synthetic air. BCNF sensor was found highly stable and very selective toward CO2 in presence of SO2 (0 - 20 ppm)