Significant variation of surface spin polarization through group IV atom (C, Si, Ge, Sn) adsorption on Fe<sub>3</sub>O<sub>4</sub>(100)

Sun, Xu; Li, S. D.; Wang, B.; Kurahashi, Mitsunori; Pratt, Andrew; Yamauchi, Yasushi

doi:10.1039/c3cp53272k

Cited by 10 publications

(20 citation statements)

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“…The adsorption of group IV atoms (C, Si, Ge, Sn) on the Fe 3 O 4 ð100Þ surface has been investigated using GGA. 127 The results show that all these atoms prefer to bind on the surface oxygen atom, which has no tetrahedral Fe neighbor. The adsorption structures and energies of a single Au atom on six different terminations of the Fe 3 O 4 ð111Þ surface were computed using GGA+U.…”

Section: Surfaces and Adsorptionmentioning

confidence: 94%

Photoelectrochemical and theoretical investigations of spinel type ferrites (M_xFe_3−xO₄) for water splitting: a mini-review

et al. 2016

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Solar-assisted water splitting using photoelectrochemical cells (PECs) is one of the promising pathways for the production of hydrogen for renewable energy storage. The nature of the semiconductor material is the primary factor that controls the overall energy conversion efficiency. Finding semiconductor materials with appropriate semiconducting properties (stability, efficient charge separation and transport, abundant, visible light absorption) is still a challenge for developing materials for solar water splitting. Owing to the suitable bandgap for visible light harvesting and the abundance of iron-based oxide semiconductors, they are promising candidates for PECs and have received much research attention. Spinel ferrites are subclasses of iron oxides derived from the classical magnetite (Fe II Fe III 2 O 4) in which the Fe II is replaced by one (some cases two) additional divalent metals. They are generally denoted as M x Fe 3−x O 4 (M ¼ Ca, Mg, Zn, Co, Ni, Mn, and so on) and mostly crystallize in spinel or inverse spinel structures. In this mini review, we present the current state of research in spinel ferrites as photoelectrode materials for PECs application. Strategies to improve energy conversion efficiency (nanostructuring, surface modification, and heterostructuring) will be presented. Furthermore, theoretical findings related to the electronic structure, bandgap, and magnetic properties will be presented and compared with experimental results. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Surfaces and Adsorptionmentioning

confidence: 94%

Photoelectrochemical and theoretical investigations of spinel type ferrites (M_xFe_3−xO₄) for water splitting: a mini-review

et al. 2016

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“…In recent years Pratt, Yamauchi, and co-workers have published a series of papers [90][91][92][93][94] emission is a function of the spin-dependent DOS of the sample. The cross-section for the process is large, which makes the method extremely surface sensitive.…”

Section: Fe 3 O 4 -Half-metallicitymentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

501

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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“…This is markedly different to previous studies investigating the adsorption of atomic H, B, and C in which O1 was determined to be the most energetically preferred site. 6,9,10 NO molecules that approach a surface via the N terminal to bond with metallic atoms have also been observed for CuFe 2 O 4 (100), ZnGaAlO 4 (100) and NiO(100) substrates. [22][23][24] Fig top of a Ni atom of the NiO(100) surface with a tilted geometry using near-edge X-ray adsorption fine structure (NEXAFS) 25 and photoelectron diffraction (PED) [26][27][28] experiments.…”

Section: Resultsmentioning

confidence: 85%

“…6 Our recent calculations predict that half-metallicity can also be recovered for the Fe 3 O 4 (100) surface through C or B adsorption with a considerable presence of -100% spin-polarized states at the adsorbate. 9,10 To deposit atomic C or B though, very high temperatures are required making the preparation of this system difficult.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of the spin polarization of an Fe₃O₄(100) surface by nitric oxide adsorption

Jibran

Sun

et al. 2018

Phys. Chem. Chem. Phys.

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The geometric, electronic and magnetic properties of a nitric oxide (NO) adsorbed Fe3O4(100) surface have been investigated using density functional theory (DFT) calculations. NO molecules preferentially bond with surface Fe(B) atoms via their N atoms. The generalized gradient approximation (GGA) is not recommended to be used in such a strongly correlated system since it provides not only an overestimation of the adsorption energy and an underestimation of the Fe(B)-N bond length, but also magnetic quenching of the adsorbate and the bonded Fe(B) atoms. In contrast, a tilted geometry and magnetization of the adsorbate and the bonded Fe(B) atom are obtained after including the strong on-site Coulomb interactions through a Hubbard term (GGA+U). The spin-down 2π* states of the NO molecule are filled and broadened due to the adsorbate-substrate interaction and the molecule-molecule interaction. The surface spin polarization close to the Fermi level is expected to be greatly enhanced by the NO adsorption which has significance for interface design in spintronic devices.

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Significant variation of surface spin polarization through group IV atom (C, Si, Ge, Sn) adsorption on Fe₃O₄(100)

Cited by 10 publications

References 40 publications

Photoelectrochemical and theoretical investigations of spinel type ferrites (M_xFe_3−xO₄) for water splitting: a mini-review

Photoelectrochemical and theoretical investigations of spinel type ferrites (M_xFe_3−xO₄) for water splitting: a mini-review

Iron oxide surfaces

Enhancement of the spin polarization of an Fe₃O₄(100) surface by nitric oxide adsorption

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Significant variation of surface spin polarization through group IV atom (C, Si, Ge, Sn) adsorption on Fe3O4(100)

Cited by 10 publications

References 40 publications

Photoelectrochemical and theoretical investigations of spinel type ferrites (MxFe3−xO4) for water splitting: a mini-review

Photoelectrochemical and theoretical investigations of spinel type ferrites (MxFe3−xO4) for water splitting: a mini-review

Iron oxide surfaces

Enhancement of the spin polarization of an Fe3O4(100) surface by nitric oxide adsorption

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Product

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Significant variation of surface spin polarization through group IV atom (C, Si, Ge, Sn) adsorption on Fe₃O₄(100)

Photoelectrochemical and theoretical investigations of spinel type ferrites (M_xFe_3−xO₄) for water splitting: a mini-review

Photoelectrochemical and theoretical investigations of spinel type ferrites (M_xFe_3−xO₄) for water splitting: a mini-review

Enhancement of the spin polarization of an Fe₃O₄(100) surface by nitric oxide adsorption