SERC synergy

SERC carries out strategic research on electrochemical cells for energy conversion, gas cleaning and oxygen sensing. The projects involve improvement of existing electrodes and electrolytes or development of new electrode materials for the electrochemical cells and methods for materials characterisation.
Internal synergy between the projects is ensured by arranging meetings where the ph.d.-students can exchange knowledge, discover possibilities of cooperation as well as discuss problems.

One of the SERC Ph.D. project deals with finding new electrode materials for oxygen sensors. As a part of this the existing Pt-on-zirconia sensors will be studied for comparison. Slightly overlapping with the Ph.D. project but still apart from it, another activity is taking place which concerns sensors from a specific customer that experiences a degradation of the sensors over time in a special environment. An array of analyses including impedance spectroscopy, chemical analysis and scanning electron microscopy has been set up to study the sensors and discover the causes for the degradation.

A number of used and new sensors have been cut for XPS analysis so that the surface composition can be determined. Initial studies indicate that a significant amount of silicon is present in new sensors and that the amount increases with time in use. Silicon e.g. in the form of silicone vapours is known to poison platinum electrodes (Ehrhardt et al. 1997). The platinum paste used for electrodes is studied separately to exclude that as a source of the primary silicon. The platinum paste contains Bi that acts as a flux and since Bi-silicates easily form at the working temperature of the sensor (Armelao et al. 1998) such phases may also be present.

The project is ongoing as of December 2008 and results will be presented later.