Carbon monoxide-induced adatom sintering in a Pd–Fe3O4 model catalyst

Parkinson, Gareth S.; Novotný, Zbyněk; Argentero, Giacomo; Schmid, Michael; Pavelec, Jiří; Kosak, Rukan; Blaha, Peter; Diebold, Ulrike

doi:10.1038/nmat3667

Cited by 272 publications

(335 citation statements)

References 38 publications

(50 reference statements)

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“…Although they are also observed in the proximity of surface defects such as steps edges, this paper discusses bright protrusions other than those. Previous STM studies of a freshly prepared Fe 3 O 4 (001) surface have also observed them [5,8,21,27,28]. As a result of XPS measurements of the surface, we have observed no peaks derived from impurities such as CO and no peak shifts for O and Fe (data not shown).…”

Section: Resultssupporting

confidence: 69%

Scanning Tunneling Microscopy Study of an Altered Fe3O4(001) Thin Films Surface by Hydrogen Adsorption

Hiura

Ikeuchi

Shirini

et al. 2014

e-J. Surf. Sci. Nanotech.

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We report on changes of surface structures induced by hydrogen adsorption on a Jahn-Teller distorted magnetite (Fe3O4)(001) surface and priorities of hydrogen-adsorbed sites by means of in-situ scanning tunneling microscopy. The experiments have revealed that surface Fe cations relax toward the bulk-terminated positions by OH species formed between adsorbed-hydrogen and surface ON anion (The labeled "N"in ON denotes that the O-O distance in the surface is compressed compared with bulk). Moreover, two types of surface ON sites were found to be almost equivalent for hydrogen adsorption.

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Section: Resultssupporting

confidence: 69%

Scanning Tunneling Microscopy Study of an Altered Fe3O4(001) Thin Films Surface by Hydrogen Adsorption

Hiura

Ikeuchi

Shirini

et al. 2014

e-J. Surf. Sci. Nanotech.

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“…27 Foreign metal atoms deposited onto this surface adsorb in an oxygen-bridging site in one specific location of the unit cell. 39,[41][42][43] The force-relaxed structure of a Co adatom (Co 2+ ) in such site is shown in Figure 6(a).…”

Section: B Dft Resultsmentioning

confidence: 99%

“…Among them, based on reported work 39,[41][42][43] and our DFT calculations, we have considered the adatom site on top of two surface oxygen cations in a bridge configuration, the surface octahedral positions, and the subsurface octahedral positions. The latter, as described in the Sec.…”

Section: Discussionmentioning

confidence: 99%

Co on Fe3O4(001): Towards precise control of surface properties

Gargallo-Caballero

Martín-García

Quesada

et al. 2016

The Journal of Chemical Physics

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A novel approach to incorporate cobalt atoms into a magnetite single crystal is demonstrated by a combination of x-ray spectro-microscopy, low-energy electron diffraction, and density-functional theory calculations. Co is deposited at room temperature on the reconstructed magnetite (001) surface filling first the subsurface octahedral vacancies and then occupying adatom sites on the surface. Progressive annealing treatments at temperatures up to 733 K diffuse the Co atoms into deeper crystal positions, mainly into octahedral ones with a marked inversion level. The oxidation state, coordination, and magnetic moments of the cobalt atoms are followed from their adsorption to their final incorporation into the bulk, mostly as octahedral Co2+. This precise control of the near-surface Co atoms location opens up the way to accurately tune the surface physical and magnetic properties of mixed spinel oxides.

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“…The published binding energy of 2.25 eV and charge state of +0.6 e -were calculated using the DBT structure [262], but these values do not change significantly for the SCV structure as the local environment around the adsorption site is similar. High coverages of Pd adatoms can be achieved, which suggests the Pd-Pd dimer is unstable with respect to two adatoms (as discussed for Ag, above).…”

Section: Palladiummentioning

confidence: 99%

“…High coverages of Pd adatoms can be achieved, which suggests the Pd-Pd dimer is unstable with respect to two adatoms (as discussed for Ag, above). However, in contrast to Au and Ag, the stability of the Pd 1 /Fe 3 O 4 (001) system is highly sensitive to CO [262]. Indeed, even in a pressure of 5×10 -10 mbar CO, Pd adatoms sinter completely to form Pd nanoparticles in under an hour (see Figure 84).…”

Section: Palladiummentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

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482

463

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The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe 3 O 4 ), maghemite (γ-Fe 2 O 3 ), hematite (α-Fe 2 O 3 ), and wüstite (Fe 1-x O) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe 3 O 4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment, and because it is an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed.The best understood iron oxide surface at present is probably Fe 3 O 4 (100); the structure is known with a high degree of precision and the major defects and properties are well characterised. A major factor in this is that a termination at the Fe oct -O plane can be reproducibly prepared by a variety of methods, as long as the surface is annealed in 10 Such straightforward preparation of a monophase termination is generally not the case for other iron oxide surfaces. All available evidence suggests the oft-studied (√2×√2)R45° reconstruction results from a rearrangement of the cation lattice in the outermost unit cell in which two octahedral cations are replaced by one tetrahedral interstitial, a motif conceptually similar to well-known Koch-Cohen defects in Fe (0001) is the most studied hematite surface, but 2 difficulties preparing stoichiometric surfaces under UHV conditions have hampered a definitive determination of the structure. There is evidence for at least three terminations: a bulk-like termination at the oxygen plane, a termination with half of the cation layer, and a termination with ferryl groups. When the surface is reduced the so-called "bi-phase" structure is formed, which eventually transforms to a Fe 3 O 4 (111)-like termination. The structure of the bi-phase surface is controversial; a largely accepted model of coexisting Fe 1-x O and α-Fe 2 O 3 (0001) islands was recently challenged and a new structure based on a thin film of Fe 3 O 4 (111) on α-Fe 2 O 3 (0001) was proposed. The merits of the compet...

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Carbon monoxide-induced adatom sintering in a Pd–Fe3O4 model catalyst

Cited by 272 publications

References 38 publications

Scanning Tunneling Microscopy Study of an Altered Fe<sub>3</sub>O<sub>4</sub>(001) Thin Films Surface by Hydrogen Adsorption

Scanning Tunneling Microscopy Study of an Altered Fe<sub>3</sub>O<sub>4</sub>(001) Thin Films Surface by Hydrogen Adsorption

Co on Fe3O4(001): Towards precise control of surface properties

Iron oxide surfaces

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