WORK FUNCTION MEASUREMENTS ON CATALYST FILMS SUBJECT TO INSITU ELECTROCHEMICAL PROMOTION

In order to investigate the origin of the recently found effect of Non-Faradaic Electrochemical Modification of Catalytic Activity (NEMCA) a Kelvin probe was used to measure in situ the changes induced in the work function of Pt catalyst films deposited on doped ZrO2 and beta"-Al2O3 solid electrolytes upon electrochemical supply or removal of O2- and Na+ to or from the catalyst surface. It was found that the change in catalyst work function equals e-DELTA-V(WR) where DELTA-V(WR) is the change in the ohmic-drop-free catalyst potential with respect to a reference electrode. The experimental procedure is described and the important consequences of this result both for the work-function-probing capability of solid electrolyte cells and also for the origin of NEMCA are briefly outlined.