La2 Cu O4 (LCO) powders were used to fabricate electrodes for solid-state potentiometric N Ox sensors [LCO∫yttria-stabilized zirconia (YSZ)∫Pt], and symmetrical Pt (Pt∫YSZ∫Pt) and La2 Cu O4 (LCO∫YSZ∫LCO) cells. The impedances of the sensors and symmetrical cells were measured. Three phenomena were observed in the impedance spectra: O2 ion conduction in the YSZ electrolyte, surface conduction on the La2 Cu O4 electrode, and the electrochemical reaction of O2 at the electrode/electrolyte/gas interface. The impedance associated with O2 reduction/oxidation decreased in the presence of O2, NO, and N O2, in contrast to the potentiometric response which increased in NO, decreased in N O2, and was unaffected by changes in O2 concentration. The impedance associated with surface conduction on the La2 Cu O4 electrode was affected by NO and N O2 in much the same way as the previously reported potentiometric sensor response (ΔOCP) in terms of temperature and concentration dependencies providing evidence for an adsorption mechanism for the potentiometric response.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry