(736b) High Temperature Potentiometric O2 Sensor Based On Stabilized Zirconia and NiO Electrode

A planar O₂ potentiometric sensor was fabricated by using yttria-stabilized zirconia (YSZ) electrolyte, NiO sensing electrode and Pt reference electrode. The thin NiO films (or NiO nanofibers) of 100 nm thickness were prepared by r.f. magnetron sputtering of NiO on YSZ substrate (or by electrospinning on YSZ substrate followed by calcination). X-ray diffraction patterns suggested that NiO was coated on YSZ surface. The morphology of NiO film (or NiO nanofiber) was investigated by scanning electron microscopy and atomic force microscopy. The sensing electrode was examined for O₂ sensor operating at 500-700°C.  The linear relationship between the sensor EMF output and the logarithm of the O₂ gas concentration was observed, and the sensitivity to oxygen increased with increasing operating temperature. These results obeyed the theoretical Nernst relationship well. Finally, electrochemical impedance spectroscopy study was used to investigate the sensor mechanism, and a novel potentiometric sensor mechanism which involves surface reaction, catalysis, oxidation and reduction was suggested.

*Corresponding author: ylei@engr.uconn.edu