Structural investigations of V2O5–P2O5–CaO glass system by FT-IR and EPR spectroscopies

Ştefan, R.; Simedru, Dorina; Popa, Adriana; Ardelean, I.

doi:10.1007/s10853-011-6225-x

Cited by 11 publications

(6 citation statements)

References 22 publications

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“…4, we observe a broad resonance at g = 1.945, which is characteristic of V 4+ in Bi-VO 4 . 43 The lack of a well-defined hyperfine structure indicates strong spin-spin couplings between the V 4+ ions within the material 41,[43][44][45][46] and the simultaneous presence of structurally different V 4+ sites arising from, for example, free polarons and defect-bound polarons associated with H int and H O , as well as O vac . 47 We also detect a small background EPR signal in the as-synthesized BiVO 4 powder samples.…”

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confidence: 99%

Role of Hydrogen in Defining the n-Type Character of BiVO₄ Photoanodes

Cooper¹,

Scott²,

et al. 2016

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The roles of hydrogen impurity and oxygen vacancy defects on defining the conductivity, and hence photoelectrochemical (PEC) performance characteristics, of monoclinic scheelite bismuth vanadate (BiVO4) are investigated using a combination of experiment and theory. We find that elemental hydrogen is present as an impurity in as-synthesized BiVO4 and that increasing its concentration by annealing in H2 at temperatures up to 290 °C leads to near-complete elimination of majority carrier transport limitations, a beneficial shift in the photoanodic current onset potential, and improved fill factor. Magnetic resonance measurements reveal that hydrogen can be incorporated in at least two different chemical environments, which are assigned to interstitial and substitutional sites. Incorporation of hydrogen leads to a shift of the Fermi level toward the conduction band edge, indicating that n-type character is correlated with increased hydrogen content. This finding is in agreement with theory and reveals that hydrogen acts as a donor in BiVO4. Sub-bandgap photoluminescence is observed from as-synthesized material and is consistent with deep electronic states associated with oxygen vacancies. Hydrogen treatment leads to reduced emission from these states. These findings support the conclusion that hydrogen, rather than oxygen vacancies, is dominant in determining the n-type conductivity of BiVO4. These findings have important implications for controlling the electronic properties and functional characteristics of this promising photoanode material.

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confidence: 99%

Role of Hydrogen in Defining the n-Type Character of BiVO₄ Photoanodes

Cooper¹,

Scott²,

et al. 2016

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“…For the middle of the spectra (650-850 cm -1 ), no strong correlation between the glass composition and peak intensity is observed; however, its shape depends on the glass composition: when V , as well as various vibrations of phosphate glass network, for example, vibrations of O-P-O and O=P-O bonds [29][30][31]. Considering that the intensity of this peak increases as P 2 O 5 content grows, the main contribution might be assigned to the vibrations of PO 2 structural units [24,31].…”

Section: Wavelength Range From 400 To 1010 CM -1mentioning

confidence: 94%

“…, a gradual degeneration of the most intense peak is observed, and it shifts towards lower wavelengths (from 757 to 742 cm -1 for V 2 O 5 content of 95 and 75 mol %, respectively). The following vibrations can be excited in this spectrum area: stretching vibrations of P-O-P [24,31] and V-O-P [32] bonds and the vibrations of the vanadium-oxygen network such as asymmetric stretching vibrations of VO 2 groups in VO 4 tetrahedra [30,33]. Since the vibrations of phosphate and vanadate networks in this area are overlapped, it is complicated to unambiguously relate the peaks obtained by spectra deconvolution.…”

Section: Wavelength Range From 400 To 1010 CM -1mentioning

confidence: 99%

Structural changes in V₂O₅-P₂O₅ glasses: non-constant force field molecular dynamics and IR spectroscopy

2021

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Quasi-binary phosphate-vanadate glasses have been studied by both IR spectroscopy and a novel method of molecular dynamics with a non-constant force field. This method is used for the self-assembly of structural models of glasses. The obtained models and the glass network structure are analyzed quantitatively using element distribution by the number of R–O–R bonds (R is phosphorous or vanadium) and 4-, 6-, and 8-membered cycles. The bends on the concentration dependences of atoms distribution in the second coordination sphere agree well with changing the shape of IR spectra. Based on the cycle analysis, the formation of cycles is shown to be more characteristic for vanadate fragments that can form 4-membered cycles, which, according to Zachariasen’s rule, negatively affects glass-forming ability.

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“…Further, we obtained the AGEs and NADH percentages ratio (%) of the total studied fluorescent serum compounds (Stefan et al, 2012).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Fluorophores advanced glycation end products (AGEs)-to-NADH ratio is predictor for diabetic chronic kidney and cardiovascular disease

Ciobanu

Olar

Ştefan

et al. 2015

Journal of Diabetes and its Complications

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Structural investigations of V2O5–P2O5–CaO glass system by FT-IR and EPR spectroscopies

Cited by 11 publications

References 22 publications

Role of Hydrogen in Defining the n-Type Character of BiVO₄ Photoanodes

Role of Hydrogen in Defining the n-Type Character of BiVO₄ Photoanodes

Structural changes in V₂O₅-P₂O₅ glasses: non-constant force field molecular dynamics and IR spectroscopy

Fluorophores advanced glycation end products (AGEs)-to-NADH ratio is predictor for diabetic chronic kidney and cardiovascular disease

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Structural investigations of V2O5–P2O5–CaO glass system by FT-IR and EPR spectroscopies

Cited by 11 publications

References 22 publications

Role of Hydrogen in Defining the n-Type Character of BiVO4 Photoanodes

Role of Hydrogen in Defining the n-Type Character of BiVO4 Photoanodes

Structural changes in V2O5-P2O5 glasses: non-constant force field molecular dynamics and IR spectroscopy

Fluorophores advanced glycation end products (AGEs)-to-NADH ratio is predictor for diabetic chronic kidney and cardiovascular disease

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Product

Resources

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Role of Hydrogen in Defining the n-Type Character of BiVO₄ Photoanodes

Role of Hydrogen in Defining the n-Type Character of BiVO₄ Photoanodes

Structural changes in V₂O₅-P₂O₅ glasses: non-constant force field molecular dynamics and IR spectroscopy