Raman scattering study of charge ordering in  -Ca0.33V2O5

Popović, Zdenka; Konstantinović, M.J.; Moshchalkov, Victor; Isobe, Masahiko; Ueda, Y.

doi:10.1088/0953-8984/15/6/101

Cited by 27 publications

(27 citation statements)

References 26 publications

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“…Our results are in good agreement with the previous experimental results and theoretical calculation [40]. After the alkali treatment, the Raman spectrum is similar to that of pristine V2C MXene except for a small peak that is observed at ~165 cm −1 , which might be associated with the insertion of potassium ions and/or V−O vibrations originating from surface oxidation [42,43].…”

Section: Resultssupporting

confidence: 91%

Porous MXenes enable high performance potassium ion capacitors

et al. 2019

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High power K + ion capacitors have great potential in various large-scale applications because of the cost advantages and the low redox potential of K/K + . However, the large ionic radius of potassium brings huge challenges for the development of suitable electrode materials.Here we demonstrate a general strategy for preparing porous MXene electrodes that can significantly enhance K + storage performance. Using V2C MXene as a model system, we show that the K + ion storage capacity can be greatly boosted by a simple sequential acid/alkali treatment.The resulting product, K-V2C, not only delivers a capacity of 195 mAh g -1 (in contrast to 98 mAh g -1 of pristine V2C) at 50 mA g -1 , but also good rate performance. The charge storage mechanism was carefully studied and is shown to involve a solvent co-intercalation process. In addition, full cells were fabricated by coupling the K-V2C anode and Prussian blue analogous (KxMnFe(CN)6) cathode, which can work at a high average operating voltage of ~3.3 V within a wide range (0.01 V to 4.6 V). Moreover, the devices can achieve a high energy density of 145 Wh kg −1 at a power density of 112.6 W kg −1 , suggesting that K-V2C, and other porous MXenes prepared by our approach, are promising electrodes in mobile ion capacitors.

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Section: Resultssupporting

confidence: 91%

Porous MXenes enable high performance potassium ion capacitors

et al. 2019

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“…Figure b represents the crystal structure of the tunnel β‐Ca x V 2 O 5 phase which belongs to the monoclinic space group C 2/ m . It employs a characteristic V 2 O 5 framework constructed by the edge/corner sharing VO 5 square pyramid and VO 6 octahedra and the Ca ions are located at the enclosed tunnel sites along the crystallographic b ‐axis formed by the V 2 O 5 framework . The tunnel vanadium bronze has a strict stoichiometric ( x ≈0.33) composition because two equivalent sites for Ca cannot be occupied simultaneously …”

Section: Resultsmentioning

confidence: 99%

Long Straczekite δ‐Ca_0.24V₂O₅⋅H₂O Nanorods and Derived β‐Ca_0.24V₂O₅ Nanorods as Novel Host Materials for Lithium Storage with Excellent Cycling Stability

Zhou

Zhang

et al. 2017

Chemistry A European J

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Nanorods of δ-Ca V O ⋅H O, a straczekite group mineral with an open double-layered structure, have been successfully fabricated by a facile hydrothermal method and can be transformed into the tunnel β geometry (β-Ca V O ) through a vacuum annealing treatment. The generated β-Ca V O still preserves the nanorod construction of δ-Ca V O ⋅H O without substantial sintering and degradation of the nanostructure. As cathode materials, both calcium vanadium bronzes exhibit high reversible capacity, good rate capability, as well as superior cyclability. Compared with the hydrated vanadium bronze, the β-Ca V O nanorods show better cycling performance (81.68 and 97.93 % capacity retention after 200 cycles at 100 and 400 mA g , respectively) and excellent long-term cyclic stability with an average decay of 0.035 % per cycle over 500 cycles at 500 mA g . Note that the double-layered δ-Ca V O ⋅H O electrode irreversibly converts into β-Ca V O phase during the initial Li insertion/extraction process, while in contrast, the β-phase calcium vanadium bronze electrode shows excellent structural stability during cycling. The excellent electrochemical performance demonstrates that the two calcium vanadium bronzes are potential cathode candidates for rechargeable lithium-ion batteries.

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“…The Raman spectrum of uncoated as-prepared β-Pb x V 2 O 5 nanowires is characterized by bands arising from phonon modes involving bond-bending and chaining of the V 2 O 5 framework below 500 cm −1 and bond-stretching of the framework above 500 cm −1 . 54 The low-frequency modes around 175 cm −1 correspond to external motions of [VO 5 ] and [VO 6 ] polyhedra wherein these units are collectively displaced with respect to each other. 40,55 In contrast, the band at 951 cm −1 likely derives from the V−O stretching mode localized within the [VO 5 ] square pyramids of β-Pb x V 2 O 5 .…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Integrating β-Pb_0.33V₂O₅ Nanowires with CdSe Quantum Dots: Toward Nanoscale Heterostructures with Tunable Interfacial Energetic Offsets for Charge Transfer

et al. 2015

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Achieving directional charge transfer across semiconductor interfaces requires careful consideration of relative band alignments. Here, we demonstrate a promising tunable platform for light harvesting and excited-state charge transfer based on interfacing β-Pb x V 2 O 5 nanowires with CdSe quantum dots. Two distinct routes are developed for assembling the heterostructures: linker-assisted assembly mediated by a bifunctional ligand and successive ionic layer adsorption and reaction (SILAR). In the former case, the thiol end of a molecular linker is found to bind to the quantum dot surfaces, whereas a protonated amine moiety interacts electrostatically with the negatively charged nanowire surfaces. In the alternative SILAR route, the surface coverage of CdSe nanostructures on the β-Pb x V 2 O 5 nanowires is tuned by varying the number of successive precipitation cycles. High-energy valence band X-ray photoelectron spectroscopy measurements indicate that "mid-gap" states of the β-Pb x V 2 O 5 nanowires derived from the stereoactive lone pairs on the intercalated lead cations are closely overlapped in energy with the valence band edges of CdSe quantum dots that are primarily Se 4p in origin. Both the midgap states and the valence-band levels are in principle tunable by variation of cation stoichiometry and particle size, respectively, providing a means to modulate the thermodynamic driving force for charge transfer. Steady-state and time-resolved photoluminescence measurements reveal dynamic quenching of the trapstate emission of CdSe quantum dots upon exposure to β-Pb x V 2 O 5 nanowires. This result is consistent with a mechanism involving the transfer of photogenerated holes from CdSe quantum dots to the midgap states of β-Pb x V 2 O 5 nanowires. ■ INTRODUCTIONTuning interfaces between disparate semiconductors, between molecules and semiconductor surfaces, and between semiconductors and metals remains of paramount importance for electronics, optoelectronics, photocatalysis, photovoltaics, and electrochemical energy storage. 1−4 Interfaces assume special significance for nanostructures given their high surface-tovolume ratios. Nanoscale heterostructures are of particular interest for photocatalysis owing to the tunability of the energies of the valence and conduction band edges of semiconductors as a function of finite size and doping, which allows for different components performing discrete functions to be assembled within modular platforms to facilitate sequential light-harvesting, charge transfer, and catalytic processes. 4,5 To enable programmable cascades of directional charge transfer reactions, heterostructures need to be designed keeping in mind several considerations such as the nature of the interface, the thermodynamics of band alignments between different components, and the kinetics of charge transfer. In this work, we have sought to design nanoscale heterostructures to exploit the availability of midgap states energetically positioned between the valence and conduction bands of a transition metal oxi...

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Raman scattering study of charge ordering in -Ca_0.33V₂O₅

Cited by 27 publications

References 26 publications

Porous MXenes enable high performance potassium ion capacitors

Porous MXenes enable high performance potassium ion capacitors

Long Straczekite δ‐Ca_0.24V₂O₅⋅H₂O Nanorods and Derived β‐Ca_0.24V₂O₅ Nanorods as Novel Host Materials for Lithium Storage with Excellent Cycling Stability

Integrating β-Pb_0.33V₂O₅ Nanowires with CdSe Quantum Dots: Toward Nanoscale Heterostructures with Tunable Interfacial Energetic Offsets for Charge Transfer

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Raman scattering study of charge ordering in -Ca0.33V2O5

Cited by 27 publications

References 26 publications

Porous MXenes enable high performance potassium ion capacitors

Porous MXenes enable high performance potassium ion capacitors

Long Straczekite δ‐Ca0.24V2O5⋅H2O Nanorods and Derived β‐Ca0.24V2O5 Nanorods as Novel Host Materials for Lithium Storage with Excellent Cycling Stability

Integrating β-Pb0.33V2O5 Nanowires with CdSe Quantum Dots: Toward Nanoscale Heterostructures with Tunable Interfacial Energetic Offsets for Charge Transfer

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Raman scattering study of charge ordering in -Ca_0.33V₂O₅

Long Straczekite δ‐Ca_0.24V₂O₅⋅H₂O Nanorods and Derived β‐Ca_0.24V₂O₅ Nanorods as Novel Host Materials for Lithium Storage with Excellent Cycling Stability

Integrating β-Pb_0.33V₂O₅ Nanowires with CdSe Quantum Dots: Toward Nanoscale Heterostructures with Tunable Interfacial Energetic Offsets for Charge Transfer