TY - JOUR

T1 - Stability and Catalytic Performance of Reconstructed Fe3O4 (001) and Fe3O4 (110) Surfaces during Oxygen Evolution Reaction

AU - Müllner, M.

AU - Riva, M.

AU - Kraushofer, F.

AU - Schmid, M.

AU - Parkinson, G.S.

AU - Mertens, S.F.L.

AU - Diebold, U.

PY - 2019/4/4

Y1 - 2019/4/4

N2 - 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.

AB - 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.

KW - Alkalinity

KW - Artificial photosynthesis

KW - Atomic force microscopy

KW - Crystal structure

KW - Electrons

KW - Iron oxides

KW - Oxygen

KW - Scanning tunneling microscopy

KW - Single crystal surfaces

KW - Sodium hydroxide

KW - Surface reactions

KW - X ray photoelectron spectroscopy

KW - Catalytic performance

KW - Electrically conductive

KW - Electrochemical reactions

KW - Mechanistic studies

KW - Oxidizing conditions

KW - Oxygen evolution reaction

KW - Reaction mechanism

KW - Structure and properties

KW - Magnetite

U2 - 10.1021/acs.jpcc.8b08733

DO - 10.1021/acs.jpcc.8b08733

M3 - Journal article

VL - 123

SP - 8304

EP - 8311

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 13

ER -