The NO2 response of solid electrolyte sensors made using nano-sized LaFeO3 electrodes

Electrochemical cells were prepared coupling an oxygen ionic conductor (Y2O3-stabilized ZrO2:YSZ) with a semiconducting oxide (LaFeO3) electrode. Pt was used as the counter electrode. These devices showed promising NO2 sensing performance at 400 and 450°C. The electromotive force (EMF) value of the (Pt)LaFeO3/YSZ/Pt sensor increased in NO2 atmospheres with a fast response time. The polarization curves showed non-linear behavior in air and NO2. The non-linearity was attributed to the potential drop at the electrode interfaces. Electrochemical impedance spectroscopy (EIS) analysis of the devices showed that the resistance and reactance at the electrolyte/electrode interface decreased upon introduction of 100 ppm NO2 in air, because of a lower electrode overvoltage.