The oxygen transfer process on solid oxide/noble metal electrodes, studied with impedance spectroscopy, dc polarization and isotope exchange
✍ Scribed by B.A. Boukamp; B.A. van Hassel; I.C. Vinke; K.J. De Vries; A.J. Burggraaf
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 892 KB
- Volume
- 38
- Category
- Article
- ISSN
- 0013-4686
No coin nor oath required. For personal study only.
✦ Synopsis
Abstrset-The electrochemical oxygen transfer process at the yttria stabilixed xirconia (YSZ) and Feimplanted YSZ, and at the erbia stabilized bismuth oxide (BE25) surface is studied with dc polarization and impedance spectroscopy using gold electrodes, and with '*O gas phase exchange. The surface modification by Fe-implantation increase8 the exchange current density up to a factor of 50, but analysis of the impedance spectra at dilTerent polarization levels indicates that the type of electrode reaction is not changed by the implantation. Inductive effects at cathodic polarizations are interpreted with a stepwise transfer of electrons. Isotope exchange experiments show an increase in adsorption/reaction sites at the surface after implantation. The high exchange current density, I,, for BE25 is independent of type of electrode but does depend on electrode morphology. I, can be equated to the surface oxygen exchange rate, indicating that the entire electrolyte surface is active in the electrode exchange process. Qualitative interpretation of the impedance spectra measured at ditTerent levels of polarization result8 in a model where adsorbed oxygen species diffuse over the oxide surface, while charge transfer occurs across the surface.