USE OF A NOVEL TEMPERATURE-PROGRAMMABLE ELECTROCHEMICAL-CELL TO INVESTIGATE ELECTROCHEMICALLY GENERATED SURFACE OXYGEN SPECIES

A novel temperature-programmable electrochemical cell was designed and constructed. The cell consisted of a CaO-stabilised zirconia solid oxide electrolyte, an Ag cathode exposed to air, and an Ag, Au, or solid oxide anode. Electrochemical oxygen ion pumping (EOP) from the cathode could be performed in both constant-current and constant-potential-difference modes at a constant temperature or during a temperature programme. The gas exiting the anode chamber was analysed by a quadrupole mass spectrometer (QMS). During EOP, the O-2 detected by the QMS was found to be related faradaically to the charge passed across the electrolyte. Oxygen species formed on the anode surface during EOP were investigated by performing O-2 temperature-programmed desorption experiments with working anodes. Oxygen species derived electrochemically gave rise to a low-temperature desorption peak not seen for species formed from gaseous O-2. This electrochemically generated oxygen species may be related to the surface species postulated to be responsible for the non-faradaic electrochemical modification of catalytic activity effect (Vayenas, C. G., Bebelis, S., Yentekakis, I. V., and Lintz, H.-G., Catal. Today 11, 297(1992)). (C) 1995 Academic Press, Inc.