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O: Fachverband Oberflächenphysik

O 49: Oxide Surfaces 1

O 49.8: Vortrag

Mittwoch, 7. September 2022, 16:45–17:00, S053

Complexion Induced Active Phase Evolution in High-Temperature Solid Oxide Cells — •Hanna Türk, Franz-Philipp Schmidt, Thomas Götsch, Robert Schlögl, Axel Knop-Gericke, Thomas Lunkenbein, Christoph Scheurer, and Karsten Reuter — Fritz-Haber-Institut der MPG, Berlin, Germany

Solid oxide cells (SOCs) are among the most efficient technologies for energy-to-hydrogen conversion from fluctuating renewable electricity sources. While SOCs are in principle well adapted to intermittent operation, cell performance and lifetime in electrolysis mode is severely limited by degradation of the anode. This degradation goes hand in hand with the oxygen evolution reaction (OER) taking place at the triple-phase boundary (TPB) between the anode, the solid electrolyte and the gas phase. Up to now, the atomistic structure of this active catalyst region is essentially unknown though, which prevents a detailed analysis of the actual degradation mechanisms.

Recently, we took the first step in elucidating the TPB structure by revealing a complexion at the underlying solid|solid interface of the sintered anode[1], featuring partial amorphization and varying elemental distributions deviating from the confining bulk phases. Based on this finding, we now expand our force field based Monte-Carlo simulations to the OER active site. Our experimentally validated results show unexpected compositional changes with respect to the thermodynamic equilibrium, that combined with a spatially resolved diffusion study indicate a hitherto unknown deactivation mechanism of the anode.

[1] H. Türk et al., Adv. Mater. Interfaces 8, 2100967 (2021).