Interlayer coordination environments of iron, cobalt, and nickel in vanadyl phosphate dihydrate, VOPO4.2H2O, intercalation compounds

Antonio, Mark R.; Barbour, R. L.; Blum, P.

doi:10.1021/ic00255a012

Cited by 71 publications

(31 citation statements)

References 2 publications

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“…Figure 3 shows the X-Ray diffraction pattern of the unsupported VPO-u sample. The pattern is very similar to the one reported in the bibliography for the VOP04*2H20 (17,35). The assignment for the reflections agrees with that reported by Bordes et al (14), except for the absence of the (101) reflection.…”

Section: Catalyst Characterizationsupporting

confidence: 89%

“…the n(V=O) frequency is strongly influenced by the vanadium valence state: the n(VV=O) is placed at around (1000-1030) cm-1 and n(VIV=O) around (980-1000) cm-I (17,35). The two bands at 980 and 1014 cm-1 can represent two different vanadium valence state which arise from the redox intercalation process.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

“…The intercalation of Li cations between the layers of VOP04*2H20 can be achieved by a redox process in which the salt of the cation and a reducing anion is dissolved in a suspension with VOP04*2H20 (17,34,35). The anion reduces the Vv to Vrv and the cation is driven to the interlayer space to balance the electric charge of the solid.…”

Section: -1 P a R T I A L Oxidation O F Methane To Formaldehyde On mentioning

confidence: 99%

“…The water is driven off the inter laminar space at low temperatures (< 100 "C) yielding aI-VOPO, (17). The aj-VOP04 can be described as VOPO4 layers lying in the ab plane as well, but the VO6 octahedra are also sharing the axial 0 atoms with other V atoms forming chains of octahedra running along the c axis (18)(19)(20).…”

Section: Introduction To Eachmentioning

confidence: 99%

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Transient studies of low temperature catalysts for methane conversion. Final report, [September 1992--March 1996]

Wolf¹

1996

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Section: Catalyst Characterizationsupporting

confidence: 89%

Section: Catalyst Characterizationmentioning

confidence: 99%

Section: -1 P a R T I A L Oxidation O F Methane To Formaldehyde On mentioning

confidence: 99%

Section: Introduction To Eachmentioning

confidence: 99%

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Transient studies of low temperature catalysts for methane conversion. Final report, [September 1992--March 1996]

Wolf¹

1996

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“…The presence of the 002 plane throughout the electrochemical reduction is consistent with robust stability of the VPO sublattice in this material. Robust structural integrity of the VPO host matrix with intercalation of water and mono-and divalent cations has been reported for the family of M x VOPO 4 •yH 2 23,[38][39][40] At 0.72 electron equivalents, the intensity of diffracted X-rays on the 004 (near 2θ = 27.3…”

Section: Electrochemicalmentioning

confidence: 99%

Electrochemical Reduction of Ag_0.48VOPO₄: A Mechanistic Study Employing X-Ray Absorption Spectroscopy and X-Ray Powder Diffraction

Kirshenbaum

Menard

Kim

et al. 2015

J. Electrochem. Soc.

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The electrochemical reduction of Ag 0.48 VOPO 4 • 1.9H 2 O is accompanied by vanadium and silver oxidation state changes, characterized with X-ray absorption spectroscopy (XAS), and by structural changes, characterized with X-ray powder diffraction (XRD). The XAS data suggest that the initial reduction process, involving 0 to 0.5 electron equivalents, involved primarily the reduction of vanadium cations, while most of the silver cations are reduced between 0.5 to 1.0 electron equivalents. The XRD data display significant intensity decreases of absorbances associated with the 004 and 006 planes upon electrochemical reduction, consistent with a reduction-displacement of Ag + with insertion of Li + . Retention of intensity of the absorbance associated with the 002 plane, with only minor decrease in interlayer spacing, indicates retention of the VOPO 4 sublattice structure. Uncovering the details of the discharge mechanism of bimetallic cathode materials such as Ag 0.48 VOPO 4 should enable the design of future high current cathodes for secondary batteries displaying an enhanced current capacity based on a reduction-displacement strategy. Polyanionic frameworks form the basis of a number of battery electrode materials with desirable electrochemical properties.1 For example, commercial cells using LiFePO 4 chemistry have found success owing to both high charge and discharge current capability. Unfortunately, these materials can display low electrical and ionic conductivities; fortunately, the use of a conductive additive such as carbon can mitigate these issues. However, the use of conductive additives may increase production costs and negatively affect energy density. 3,4 In addition to conductive additives, low electrical conductivities of electroactive electrode materials can be addressed by exploiting electrode electrochemistries that form conductive metallic networks in situ. Specifically, we established through impedance experiments that the metallic particles formed upon reduction of some bimetallic cathode materials can enhance the conductivity by several orders of magnitude. 5 We successfully extended this strategy to four different members of the material family of silver vanadium phosphorous oxides, Ag 2 VO 2 PO 4 , 21 This strategy should lead to a variety of future battery materials, especially for high current applications.To delineate the discharge process in bimetallic materials, the oxidation state changes associated with the two metal cations as a function of discharge should be obtained. Using X-ray absorption spectroscopy (XAS), the oxidation state as well as the local environment can be measured nondestructively. XAS measurements of LiFePO 4 have been used to show the irreversibility and partial formation of FePO 4 during cycling. 22 There have also been several previous studies on silver vanadium phosphate compounds using XAS to study Ag 2 VO 2 PO 4 , 7 and Ag 2 VP 2 O 8 11 in which the effect of discharge rate on the ratio of V/Ag reduction was determined. * Electrochemical Society Active Membe...

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Water/Ethanol Displacement Reactions in Vanadyl Phosphate

Beneš¹,

Melánová

Čapková

et al. 1999

Eur. J. Inorg. Chem.

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Interlayer coordination environments of iron, cobalt, and nickel in vanadyl phosphate dihydrate, VOPO4.2H2O, intercalation compounds

Cited by 71 publications

References 2 publications

Transient studies of low temperature catalysts for methane conversion. Final report, [September 1992--March 1996]

Transient studies of low temperature catalysts for methane conversion. Final report, [September 1992--March 1996]

Electrochemical Reduction of Ag_0.48VOPO₄: A Mechanistic Study Employing X-Ray Absorption Spectroscopy and X-Ray Powder Diffraction

Water/Ethanol Displacement Reactions in Vanadyl Phosphate

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Interlayer coordination environments of iron, cobalt, and nickel in vanadyl phosphate dihydrate, VOPO4.2H2O, intercalation compounds

Cited by 71 publications

References 2 publications

Transient studies of low temperature catalysts for methane conversion. Final report, [September 1992--March 1996]

Transient studies of low temperature catalysts for methane conversion. Final report, [September 1992--March 1996]

Electrochemical Reduction of Ag0.48VOPO4: A Mechanistic Study Employing X-Ray Absorption Spectroscopy and X-Ray Powder Diffraction

Water/Ethanol Displacement Reactions in Vanadyl Phosphate

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Electrochemical Reduction of Ag_0.48VOPO₄: A Mechanistic Study Employing X-Ray Absorption Spectroscopy and X-Ray Powder Diffraction