Detecting CO2 at ppm level in synthetic air using mixed conducting double perovskite-type metal oxides

作者：Mulmi Suresh; Hassan Azfar; Pereira Almao Pedro; Thangadurai Venkataraman^*

来源：Sensors and Actuators B: Chemical , 2013, 178: 598-605.

DOI：10.1016/j.snb.2012.12.120

• CO2 sensor
• Mixed conductor
• BaCa0.33 Nb-0.34 Fe-0.33 O3-delta
• Resistance-type sensor
• In situ high temperature PXRD
• AC impedance spectroscopy

Here, we report a novel double perovskite-type BaCa0.33Nb0.34Fe0.33O3-delta (Fe-BCN) as a CO2 sensor at ppm level in a mixture of 21% O-2 in N-2 (dry synthetic air) working at 500-700 degrees C. Powder X-ray diffraction (PXRD) was used to confirm the formation of cubic double perovskite-type structure. In situ PXRD measurement under CO2 showed excellent chemical stability in the temperature range of 25-800 degrees C. A significant decrease in total impedance (resistance) was observed upon exposure to CO2 (ppm level) in synthetic air using AC impedance spectroscopy. Fe-BCN showed a fast response (t90 similar to 4 min) when 1500 ppm CO2 was introduced. The sensor response was found to be linear over the investigated range in the log I vs. log pCO(2). Fe-substitution in BaCa0.33Nb0.67O3 (BCN) is critical for the observed CO2 sensor properties since BCN exhibited a poor response under the identical sensor measurement conditions. The CO2 sensor mechanism was established using mass spectrometry (MS) in combination with DC measurements. The long-term sensor performance was studied for Fe-BCN and re-assured high sensitivity, stability and reliability.

• 出版日期2013-3-1