Transition metal oxide (Ni, Co, Fe)-tin oxide nanocomposite sensing electrodes for a mixed-potential based NO₂ sensor

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>A mixed-potential based sensor utilizing transition metal oxide (Ni, Co, Fe)-tin oxide nanocomposite sensing electrodes are fabricated for the first time and investigated for the gas sensing performance towards the highly toxic nitrogen dioxide. The nanocomposites are synthesized by solvo-combustion route and characterized for the physical, gas sensing and electrochemical properties in a temperature range of 600–700 ℃. The sensor equipped with Fe<SUB>2</SUB>O<SUB>3</SUB>-SnO<SUB>2</SUB> (Fe:Sn = 2:1) nanocomposite sensing electrodes sintered at 1000 ℃ shows the maximum response of 60 mV towards 100 ppm NO<SUB>2</SUB> with a relatively fast response and recovery dynamics at an operating temperature of 650 ℃. The sensor also shows a linear dependence of response over the logarithm of NO<SUB>2</SUB> concentration with a sensitivity of ∼44 mV/decade. Additionally, the oxygen concentration dependence, cyclability and cross-sensitivity towards interfering gases are also investigated. Finally, the sensing mechanism and electrochemical activity of the sensing electrodes are studied using polarization curve measurement and electrochemical impedance spectroscopy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Mixed-potential based sensor utilizing transition metal oxide (Ni, Co, Fe)-tin oxide nanocomposite sensing electrodes. </LI> <LI> Fe<SUB>2</SUB>O<SUB>3</SUB>-SnO<SUB>2</SUB> nanocomposite sensing electrode responded 60mV towards 100ppm NO<SUB>2</SUB> at 650 ℃. </LI> <LI> The sensitivity of the sensor was found to be 44 mV/dec. in 10-100 ppm NO<SUB>2</SUB> concentration. </LI> <LI> The sensor displayed a low oxygen conc. dependence, high selectivity and high cyclability. </LI> <LI> Sensing mechanism and key parameters determining the sensing performance are discussed in details. </LI> </UL> </P>