X‐Ray Absorption Fine Structure Spectra and the Oxidation State of Nickel in Some of Its Oxycompounds

Mansour, A. N.; Melendres, C. A.; Pankuch, Mark; Brizzolara, Robert A.

doi:10.1149/1.2054990

Cited by 74 publications

(67 citation statements)

References 2 publications

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“…When this bond length is placed on the calibration curve, an oxidation state between +3 and +4 is indicated (Capehart et a/.,1991& O'Grady et al, 1996. This is corroborated by observing an analogous, previously established linear shift in the Ni K-edge energy to higher values with increasing Ni valency (Mansour et al, 1994). In our work, both the near edge structure (XANES) and EXAFS are used to construct such calibration curves in order to interpret the behaviour of nickel hydroxide films as they are overcharged and then discharged.…”

Section: Introductionsupporting

confidence: 84%

In situ EXAFS study of nickel hydroxide electrodes during discharge

Farley¹,

Gurman²,

Hillman³

1999

J Synchrotron Radiat

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The energy dispersive EXAFS technique has been used to determine the structure of a nickel hydroxide film in situ during the discharge process. Each measurement of the nickel K-edge absorption took approximately 150 s so that the process could be followed accurately. We report changes in the energy of the nickel edge, which gives the charge state of nickel ions in the electrode, and changes in the local structure around the nickel atoms during the discharge process. These variations are correlated with the total charge on the electrode.

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Section: Introductionsupporting

confidence: 84%

In situ EXAFS study of nickel hydroxide electrodes during discharge

Farley¹,

Gurman²,

Hillman³

1999

J Synchrotron Radiat

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show abstract

“…4b), it is apparent that the edge shifts by approximately 3 eV to a lower energy. While this is consistent with reduction of the Ni metal center without applied potential [42][43][44] , structural and electronic factors could contribute and are examined in more detail via EXAFS fitting (vide infra). Further shifting of the edge toward lower energies is observed with the application of pre-catalytic (0 V) and catalytic (−0.76 V) potentials.…”

Section: Resultsmentioning

confidence: 52%

Dynamic evolution and reversibility of single-atom Ni(II) active site in 1T-MoS2 electrocatalysts for hydrogen evolution

et al. 2020

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1T-MoS 2 and single-atom modified analogues represent a highly promising class of low-cost catalysts for hydrogen evolution reaction (HER). However, the role of single atoms, either as active species or promoters, remains vague despite its essentiality toward more efficient HER. In this work, we report the unambiguous identification of Ni single atom as key active sites in the basal plane of 1T-MoS 2 (Ni@1T-MoS 2) that result in efficient HER performance. The intermediate structure of this Ni active site under catalytic conditions was captured by in situ X-ray absorption spectroscopy, where a reversible metallic Ni species (Ni 0) is observed in alkaline conditions whereas Ni remains in its local structure under acidic conditions. These insights provide crucial mechanistic understanding of Ni@1T-MoS 2 HER electrocatalysts and suggest that the understanding gained from such in situ studies is necessary toward the development of highly efficient single-atom decorated 1T-MoS 2 electrocatalysts.

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“…Sn-metal chemistry absorption edge position of the species under investigation to the regression line (see, e.g. Chen et al, 1994, Mansour et al, 1994. In our case, this interpolation leads to a value of about 3.5 ± 0.2 for the oxidation state of the tin ions in chemically prepared Sn 3 N 4 .…”

Section: Snomentioning

confidence: 56%

XAFS investigations of tin nitrides

Lützenkirchen‐Hecht¹,

Scotti²,

Jacobs³

et al. 2001

J Synchrotron Radiat

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Tin nitrides (Sn3N4) prepared by the reaction of Sn-halides with KNH2 in liquid ammonia and a subsequent vacuum annealing procedure were investigated with transmission mode XAFS experiments. While the near edge data suggest the presence of a univalent Sn-compound with a valency close to +4, the analysis of the extended X-ray absorption fine structure proves the presence of two different local Sn sites in this crystal structure: While Sn(1) is surrounded by 4 nitrogen in a distance of 2.06 A, each Sn(2) ion is coordinated with 6 nitrogen at about 2.17 A radial distance.

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X‐Ray Absorption Fine Structure Spectra and the Oxidation State of Nickel in Some of Its Oxycompounds

Cited by 74 publications

References 2 publications

In situ EXAFS study of nickel hydroxide electrodes during discharge

In situ EXAFS study of nickel hydroxide electrodes during discharge

Dynamic evolution and reversibility of single-atom Ni(II) active site in 1T-MoS2 electrocatalysts for hydrogen evolution

XAFS investigations of tin nitrides

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