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M. Müllner, M. Riva, F. Kraushofer, M. Schmid, G. Parkinson, S. Mertens, U. Diebold:
"Stability and Catalytic Performance of Reconstructed Fe₃O₄(001) and Fe₃O₄(110) Surfaces during Oxygen Evolution Reaction";
The Journal of Physical Chemistry C, 123 (2019), 8304 - 8311.

Earth-abundant oxides are promising candidates
as effective and low-cost catalysts for the oxygen evolution
reaction (OER) in alkaline media, which remains one of the
bottlenecks in electrolysis and artificial photosynthesis. A
fundamental understanding of the atomic-scale reaction
mechanism during OER could drive further progress, but a
stable model system has yet to be provided. Here we show that
Fe3O4 single crystal surfaces, prepared in ultrahigh vacuum
(UHV) are stable in alkaline electrolytein the range pH 7−14
and under OER conditions in 1 M NaOH. Fe3O4(001) and
Fe3O4(110) surfaces were studied with X-ray photoelectron
spectroscopy, low-energy electron diffraction, and scanning
tunneling microscopy in UHV, and atomic force microscopy in
air. Fe3O4(110) is found to be more reactive for oxidative water splitting than (001)-oriented magnetite samples. Magnetite is
electrically conductive, and the structure and properties of its major facets are well understood in UHV. With these newly
obtained results, we propose magnetite (Fe3O4) as a promising model system for further mechanistic studies of electrochemical
reactions in alkaline media and under highly oxidizing conditions.