Electrochemically induced surface changes on microstructured Pt films on a Solid YSZ electrolyte

Thin (500 Å) microstructured Pt films on single crystalline yttrium stabilized zirconia (YSZ) prepared by photolithography have been used to study the processes at the interface between the solid electrolyte and the Pt film when electrical potentials are applied. The experiments are performed under UHV conditions with a standard three‐electrode set‐up employing photoemission electron microscopy (PEEM) as spatially resolving method. Upon electrochemical “pumping” of oxygen by applying a positive electric potential to the Pt film we observe in PEEM a darkening of the Pt film reflecting a work function (WF) increase; a negative potential leads to a WF decrease. No time‐dependent spatial concentration profiles which would have been indicative of the slow diffusional spreading of a spillover species were observed.