Water Interaction with Iron Oxides

Dementyev, Petr; Dostert, Karl‐Heinz; Ivars‐Barceló, Francisco; O’Brien, Casey P.; Mirabella, Francesca; Schauermann, Swetlana; Li, Xiaoke; Paier, Joachim; Sauer, Joachim; Freund, Hans‐Joachim

doi:10.1002/anie.201506439

Cited by 61 publications

(70 citation statements)

References 32 publications

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“…[213], two frames of which are shown in Figure 25. An important consequence of this growth process is that annealing the surface in 18 O should result in a completely isotopically labelled surface, which can be very useful in IRAS experiments [70]. [33; 217].…”

Section: Photoelectrochemical Water Splittingmentioning

confidence: 99%

“…In addition, a peak appears at 282 K and shifts to 265 K with increasing coverage (peak γ, see Figure 67). This second order peak is attributed to recombinative desorption of water dissociated on the undercoordinated Fe tet1 cations, which exist above a FeO (111) [70]. Further work by Ranke and co-workers using IRAS [375] suggests that dissociative adsorption occurs already at 110 K, but a later STM study by Rim et al [282] claims that dissociation does not occur until 235 K, quite close to the desorption temperature.…”

Section: H 2 O/fe 3 O 4 (100)mentioning

confidence: 99%

“…Adib et al [331] studied water adsorption on the reduced selvedge of an α-Fe 2 O 3 (0001) single crystal and observed five peaks in TPD, three similar to Joseph et al [303], with the addition of peaks at 300 and 340 K. In this case it seems certain that a second termination was present, on which dissociated water is more strongly bound. Very recently, Dementyev et al [70] revisited the issue of water on Fe 3 O 4 (111) thin films using microcalorimetry, IRAS, and DFT+U calculations. The microcalorimetry data are particularly novel, giving a direct measurement of the adsorption energy of water on this surface, ≈ 101 KJ/mol at the lowest coverage.…”

Section: H 2 O/fe 3 O 4 (100)mentioning

confidence: 99%

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Iron oxide surfaces

Parkinson

2016

Surface Science Reports

491

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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Section: Photoelectrochemical Water Splittingmentioning

confidence: 99%

Section: H 2 O/fe 3 O 4 (100)mentioning

confidence: 99%

Section: H 2 O/fe 3 O 4 (100)mentioning

confidence: 99%

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Iron oxide surfaces

Parkinson

2016

Surface Science Reports

491

463

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“…OH) and v(OD) modes were rescaled by factors of 0.9789 and 0.9918 respectively; these factors were calculated using the same scheme as that specified by Freund, Sauer et al46 …”

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confidence: 99%

Surface Structure of Co₃O₄ (111) under Reactive Gas-Phase Environments

Yan

Sautet

2019

ACS Catal.

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In this work, we thoroughly examined the structure of the Co3O4(111) surface in oxidative and reductive conditions, i.e. in equilibrium with realistic pressures of O2/H2O and H2/H2O, using density functional theory with self-interaction and dispersion corrections. We found that this surface is, in fact, hydroxylated under most reaction conditions, and that subjecting the surface to H2 increases surface Co 2+ concentration. Large structural distortions facilitate the reduction and stabilization of the Co-rich termination. At 423 K, hydroxylation readily occurs on both the Orich and Co-rich surfaces even at water pressure as low as 10 -15 bar, and non-dissociated water molecules appear on the O-rich surface when water pressure is above ~10 -11 bar. Our approach showed good agreement with hybrid functional calculations and vibrational spectroscopy experiments. Under most catalytic conditions, where water is present as a reactant, product, or impurity, we predict that the Co3O4(111) surface will be hydroxylated. Hydroxyls groups and structural distortions undoubtedly play large roles in shaping the surface's catalytic properties and interaction with supported structures. The results of the study show the necessity of the inclusion of hydroxylation and surface Co concentration in computational studies of Co3O4 and provide surface structures under various conditions to aid in future studies on structure and catalytic reactivity of Co3O4(111) used as a support or as an active phase.

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“…Freund was featured here when he won the Karl Ziegler Prize . He is co‐author of a recent report in Angewandte Chemie on the interaction of water with iron oxides . Freund is on the Editorial Advisory Board of ChemPhysChem and the International Advisory Board of ChemCatChem .…”

Section: Awarded …mentioning

confidence: 99%

2016 Cottrell Scholars: W. C. K. Pomerantz, M. J. Rose, T. J. Maimone, and Y. Yu / Honorary Doctorate: H. J. Freund

2016

Angew Chem Int Ed

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Water Interaction with Iron Oxides

Cited by 61 publications

References 32 publications

Iron oxide surfaces

Iron oxide surfaces

Surface Structure of Co₃O₄ (111) under Reactive Gas-Phase Environments

2016 Cottrell Scholars: W. C. K. Pomerantz, M. J. Rose, T. J. Maimone, and Y. Yu / Honorary Doctorate: H. J. Freund

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Water Interaction with Iron Oxides

Cited by 61 publications

References 32 publications

Iron oxide surfaces

Iron oxide surfaces

Surface Structure of Co3O4 (111) under Reactive Gas-Phase Environments

2016 Cottrell Scholars: W. C. K. Pomerantz, M. J. Rose, T. J. Maimone, and Y. Yu / Honorary Doctorate: H. J. Freund

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Surface Structure of Co₃O₄ (111) under Reactive Gas-Phase Environments