Surface states and stability of Fe-containing perovskite electrodes for SOFCs/SOECs by conversion-electron Mössbauer spectroscopy

Conversion-electron Mössbauer spectroscopy analysis of model electrochemical cells, comprising porous 57Fe-enriched (La0.9Sr0.1)0.98Cr0.6Fe0.3Mg0.1O3 − δ electrodes and lanthanum gallate solid electrolyte, showed no reductive decomposition of the perovskite electrode material in H2-containing atmosphere at 1073 K, even in the steam electrolysis regime. The predominant state of iron cations in the electrode surface layers was found to remain trivalent irrespective of the oxygen partial pressure in surrounding atmosphere and polarization, whilst oxygen coordination of Fe3+ decreases on lowering electrode potential.

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► Conversion-electron Mössbauer spectroscopy is first applied to study SOFC anode.
► CEMS is sensitive to local oxygen content changes induced by electrode polarization.
► In chromite-based perovskites, Fe dopant cations remain trivalent on reduction.
► Fe3+ coordination in the porous electrode surface layers depends on polarization.
► CEMS confirms stability of IT-SOFC anodes based on Fe-doped perovskite chromites.