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Electrochemical Stability of the Reconstructed Fe 3 O 4 (001) Surface
Author(s) -
Grumelli Doris,
Wiegmann Tim,
Barja Sara,
Reikowski Finn,
Maroun Fouad,
Allongue Philippe,
Balajka Jan,
Parkinson Gareth S.,
Diebold Ulrike,
Kern Klaus,
Magnussen Olaf M.
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202008785
Subject(s) - oxygen evolution , electrochemistry , oxide , surface reconstruction , materials science , hydrogen , metal , diffraction , kinetics , electrode , magnetite , water splitting , chemistry , chemical physics , surface (topology) , catalysis , metallurgy , physics , optics , biochemistry , geometry , mathematics , organic chemistry , quantum mechanics , photocatalysis
Establishing the atomic‐scale structure of metal‐oxide surfaces during electrochemical reactions is a key step to modeling this important class of electrocatalysts. Here, we demonstrate that the characteristic (√2×√2)R45° surface reconstruction formed on (001)‐oriented magnetite single crystals is maintained after immersion in 0.1 M NaOH at 0.20 V vs. Ag/AgCl and we investigate its dependence on the electrode potential. We follow the evolution of the surface using in situ and operando surface X‐ray diffraction from the onset of hydrogen evolution, to potentials deep in the oxygen evolution reaction (OER) regime. The reconstruction remains stable for hours between −0.20 and 0.60 V and, surprisingly, is still present at anodic current densities of up to 10 mA cm −2 and strongly affects the OER kinetics. We attribute this to a stabilization of the Fe 3 O 4 bulk by the reconstructed surface. At more negative potentials, a gradual and largely irreversible lifting of the reconstruction is observed due to the onset of oxide reduction.