In-situ spectroscopic investigations of silver electrodes on stabilized zirconia

In situ spectroscopic investigations of evaporated silver films as oxygen e lectrodes on yttria stabilized zirconia (YSZ) have been performed at 550 de greesC under UHV conditions. For this purpose a new three-electrode galvani c cell with oxygen gas on the reference side has been developed. The oxygen activity at the working electrode was changed by controlling the electrode potential between working and reference electrode. Ultraviolet photoelectr on spectroscopy (UPS) was used to determine the work function change during pumping oxygen to the surface of the silver electrode. A change in valence band structure was observed during oxygen pumping. The work function incre ases and a new electronic state attributed to surface oxygen appears at a b inding energy of 3.3 eV below the Fermi energy. With X-ray photoelectron sp ectroscopy (XPS) the chemical nature of this surface oxygen species was fur ther investigated. A binding energy of the O Is core electrons was observed at 529 eV indicating the occurrence of subsurface oxygen. Scanning electro n micrographs show characteristic changes in the electrode morphology after polarization. (C) 2000 Elsevier Science B.V. All nights reserved.