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In situ study of electrochemical activation and surface segregation of the SOFC electrode material

Mixed-conducting perovskite-type electrodes which are used as cathodes in solid oxide fuel cells (SOFCs) exhibit pronounced performance improvement after cathodic polarization. The current in situ study addresses the mechanism of this activation process which is still unknown.
Huber et al. , Phys. Chem. Chem. Phys., 2012, 14, 751–758.

In the present work, we chose the perovskite-type material La0.75Sr0.25Cr0.5Mn0.5O3, which is a potential candidate for use in symmetrical solid oxide fuel cells (SFCs). For the first time,the surfaces of operating LSCrM electrodes were studied in situ (at low pressure) with spatially resolving X-ray photoelectron spectroscopy (SPEM) and quasi static secondary ion mass spectrometry (ToF-SIMS). We observed that the electrode surfaces which were annealed at 600ºC are enriched significantly in strontium. Subsequent cathodic polarization decreases the strontium surface concentration while anodic polarization increases the strontium accumulation at the electrode surface.

We propose a mechanism based on the reversible incorporation of a passivating SrO surface phase into the LSCrM lattice to explain the observed activation/deactivation process.

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In situ study of electrochemical activation and surface segregation of the SOFC electrode material La0.75Sr0.25Cr0.5Mn0.5O
A.K. Huber, M. Falk, M. Rohnke, B. Luerßen, L. Gregoratti, M. Amati, J. Janek,  Phys. Chem. Chem. Phys., 2012, 14, 751–758
Last Updated on Monday, 26 October 2015 11:56