On the shape of iron K absorption edges for monoferrites with a Me(Mg, Mn, Ni, Zn)Fe2O4 spinel structure

Safontseva, N. Yu.; Nikiforov, I. Ya.

doi:10.1134/1.1340188

Cited by 7 publications

(7 citation statements)

References 3 publications

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“…Calculations of the K-edge x-ray absorption near-edge structure (XANES) in elemental iron and MFe 2 O 4 (M: Mg, Mn, Ni, Zn) were carried out by Safontseva and Nikiforov. 96 It was shown that the Fe K-edge energy shift found experimentally occurs upon the transition from elemental iron to the spinel ferrites. This shift was demonstrated to be identically directed for ferrites with a normal and inverted spinel structure.…”

Section: Electronic Structure Of the Bulkmentioning

confidence: 99%

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: Electronic Structure Of the Bulkmentioning

confidence: 99%

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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“…Each XANES spectrum can be further divided into a pre-edge region A ͑e.g., for Mn: 6537-6545 eV͒ containing weak peaks, a main edge region B ͑for Mn:6545-6555 eV͒, and resonance peak regions C ͑for Mn: 6555-6566 eV͒ and D ͑for Mn: 6566-6580 eV͒. [23][24][25] The peaks within pre-edge region A are ascribed to 1s → 3d transitions. 23 The main absorption region B can be assigned 23,25 to the transition from 1s to p-like states of t 1u symmetry.…”

Section: Materials Characterization-mentioning

confidence: 99%

Study on Pseudocapacitance Mechanism of Aqueous MnFe[sub 2]O[sub 4] Supercapacitor

Kuo¹,

Lee²,

Wu³

2007

J. Electrochem. Soc.

105

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The electrochemical mechanism leading to the pseudocapacitance of MnFe2normalO4 in aqueous electrolyte solutions has been investigated by, in addition to electrochemical characterization, synchrotron X-ray absorption near-edge spectroscopy (XANES) and X-ray diffraction (XRD) analyses using KCl solution as the model electrolyte. The ferrite crystallites, prepared by a solution method, contain Mn and Fe ions randomly distributed over the tetrahedral and octahedral sites of the spinel structure and exhibit an average capacitance exceeding 100F∕g -ferrite. Based on the data from the in situ XANES and XRD measurements and open-circuit-potential dependence on solution pH, it is concluded that the pseudocapacitance of MnFe2normalO4 involves charge transfer at both the Mn- and Fe-ion sites, balanced by insertion/extraction of proton into/from the lattice. In addition, compared with MnO2∙nnormalH2O electrode, the ferrite exhibits a far reduced, by ∼90% , lattice expansion upon cycling.

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“…The edge energy is conventionally taken as the energy at the first inflection point, and it is known to increase with increasing valence of the transition-metal ion within the oxides. [16][17][18] It was found that the Mn ions in the as-synthesized state have a valence close to three, as the edge energy matches closely with that of Mn 2 O 3 . It has previously been shown 10 by the extended X-ray absorption fine structure ͑EXAFS͒ analysis that the Mn ions are randomly distributed over the tetrahedral and octahedral metal-ion sites within the spinel structure.…”

Section: Resultsmentioning

confidence: 72%

“…Each XANES spectrum can be divided into a pre-edge region A ͑ϳ6537-6545 eV͒ containing weak peaks, a main edge region B ͑6545-6555 eV͒, and resonance peak regions C ͑6555-6566 eV͒ and D ͑6566-6580 eV͒. [16][17][18] The peaks within preedge region A are ascribed to 1s → 3d transitions. 16 The main absorption region B can be assigned 16,18 to the transition from 1s to p-like states of t 1u symmetry.…”

Section: Resultsmentioning

confidence: 99%

“…[16][17][18] The peaks within preedge region A are ascribed to 1s → 3d transitions. 16 The main absorption region B can be assigned 16,18 to the transition from 1s to p-like states of t 1u symmetry. The edge energy is conventionally taken as the energy at the first inflection point, and it is known to increase with increasing valence of the transition-metal ion within the oxides.…”

Section: Resultsmentioning

confidence: 99%

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Electrochemical Capacitor of MnFe[sub 2]O[sub 4] with Organic Li-Ion Electrolyte

Kuo

2007

Electrochem. Solid-State Lett.

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MnFe 2 O 4 nanocrystallites have been found to exhibit capacitive characteristics in organic electrolyte containing 1 M LiPF 6 in a mixture of ethyl carbonate + ethylene methyl carbonate up to 4.5 V vs Li/Li +. The ferrite exhibits a capacitance of 126 F/g-MnFe 2 O 4 , and the symmetric-cell demonstrated a stable working voltage window of 2.5 V. In situ synchrotron spectroscopic analysis identified valence change at Mn-ion sites and a very small ͑Ͻ1%͒ extent of lattice variation, in response to Li-ion insertion/extraction. Compared with other pseudocapacitive oxides with Li-ion electrolytes, the present ferrite system has demonstrated superior cycling stability under high-rate cycling.

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On the shape of iron K absorption edges for monoferrites with a Me(Mg, Mn, Ni, Zn)Fe2O4 spinel structure

Cited by 7 publications

References 3 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

Study on Pseudocapacitance Mechanism of Aqueous MnFe[sub 2]O[sub 4] Supercapacitor

Electrochemical Capacitor of MnFe[sub 2]O[sub 4] with Organic Li-Ion Electrolyte

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On the shape of iron K absorption edges for monoferrites with a Me(Mg, Mn, Ni, Zn)Fe2O4 spinel structure

Cited by 7 publications

References 3 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

Study on Pseudocapacitance Mechanism of Aqueous MnFe[sub 2]O[sub 4] Supercapacitor

Electrochemical Capacitor of MnFe[sub 2]O[sub 4] with Organic Li-Ion Electrolyte

Contact Info

Product

Resources

About

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