Vibrational spectra of WO3·nH2O and WO3 polymorphs

Kustova, G. N.; Chesalov, Yu. A.; Plyasova, L. M.; Molina, I. Yu.; Nizovskiĭ, A. I.

doi:10.1016/j.vibspec.2010.12.004

Cited by 53 publications

(33 citation statements)

References 14 publications

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“…5 is accommodated between such layers as interlayer crystal water [4]. The origin of the bands at 1151 and 1245 cm −1 is not clear, although the bands of bending vibrations of W\OH have been observed in this spectral range [2]. From the obtained dispersions of dielectric functions in IR it can be concluded that the investigated films retain a great amount of water.…”

Section: Resultsmentioning

confidence: 85%

“…There are many crystalline hydrated tungsten trioxide compounds having the general formula nWO 3 H 2 O. Due to the wide application in modern technology, their properties are studied intensively and results have been reported for nWO 3 H 2 O compounds with n = 0.5, 1, 1.25, 2 and 3 [2][3][4][5][6][7][8]. Efficiency of electrochromic (EC) thin-film devices depends on the thicknesses of EC materials [9] as well as on their structure, optical properties and chemical purity.…”

Section: Introductionmentioning

confidence: 99%

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Optical properties of hydrated tungsten trioxide 3WO3·H2O

et al. 2014

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. Films with different thicknesses were deposited on glass substrates pre-coated with fluorine-doped tin oxide via an efficient and simple hydrothermal method. Parametric models were used to extract thicknesses and optical constants of the thin films. The WO 3 was found to be more hydrated for thicker films. Moreover, the nano-plates are larger in thicker films, which leads to a decrease of the transmission due to an increase of the scattering. Features in the obtained dielectric functions of the 3WO 3 ·H 2 O thin films were compared with the earlier published optical spectra of WO 3 and its hydrates ½WO 3 ·H 2 O and WO 3 ·H 2 O.

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Section: Resultsmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Optical properties of hydrated tungsten trioxide 3WO3·H2O

et al. 2014

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“…Significantly, these peaks are absent in the Raman spectra of the W-MMM-E catalysts, corroborating the absence of WO 3 crystallites and incorporation of well dispersed tungsten oxide species into the silica matrix. The spectra of W-MMM-E samples ( Figure 3, curves (3) and (4)) are very similar to those of the pure EISA silica ( Figure 3, curve (2)) except for the intense band at 975 cm −1 which may be attributed to vibrations of the terminal W=O bonds [55,57,58]. Raman features between 1000 and 900 cm −1 are typically observed in mono-and polytungstate species [22,41,57,58].…”

Section: mentioning

confidence: 62%

“…In spite of the distinction in the DRS-UV spectra, the Raman spectra of these samples were quite similar. The Raman spectrum of crystalline WO3 is characterized by strong bands at 808 and 720 cm −1 along with peaks at 324 and 272 cm −1 ( Figure 3, curve (1)) [33,43,55,56]. Significantly, these peaks are absent in the Raman spectra of the W-MMM-E catalysts, corroborating the absence of WO3 crystallites and incorporation of well dispersed tungsten oxide species into the silica matrix.…”

Section: mentioning

confidence: 73%

Tungsten-Based Mesoporous Silicates W-MMM-E as Heterogeneous Catalysts for Liquid-Phase Oxidations with Aqueous H2O2

et al. 2018

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Mesoporous tungsten-silicates, W-MMM-E, have been prepared following evaporation-induced self-assembly methodology and characterized by elemental analysis, XRD, N 2 adsorption, STEM-HAADF (high angle annular dark field in scanning-TEM mode), DRS UV-vis, and Raman techniques. DRS UV-vis showed the presence of two types of tungsten oxo-species in W-MMM-E samples: isolated tetrahedrally and oligomeric octahedrally coordinated ones, with the ratio depending on the content of tungsten in the catalyst. Materials with lower W loading have a higher contribution from isolated species, regardless of the preparation method. W-MMM-E catalyzes selectively oxidize of a range of alkenes and organic sulfides, including bulky terpene or thianthrene molecules, using green aqueous H 2 O 2 . The selectivity of corresponding epoxides reached 85-99% in up to 80% alkene conversions, while sulfoxides formed with 84-90% selectivity in almost complete sulfide conversions and a 90-100% H 2 O 2 utilization efficiency. The true heterogeneity of catalysis over W-MMM-E was proved by hot filtration tests. Leaching of inactive W species depended on the reaction conditions and initial W loading in the catalyst. After optimization of the catalyst system, it did not exceed 20 ppm and 3 ppm for epoxidation and sulfoxidation reactions, respectively. Elaborated catalysts could be easily retrieved by filtration and reused several times with maintenance of the catalytic behavior.

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“…[23] The lattice vibrations between 70-100 and approximately 267, 327, 708, 802 cm -1 are features of the monoclinic WO 3 phase. [24] For intermediate contents such as the 50 wt% and 80 wt% TiO 2 samples, the heterostructure formation is evidenced by the presence of typical shifts related to both TiO 2 and WO 3 . However, similarly to the XRD pattern, no WO 3 vibration mode was observed for the 90 wt% TiO 2 , confirming that in low amounts the synthesis method tends to form doped TiO 2 instead of heterostructures.…”

Section: Photocatalytic Activitymentioning

confidence: 98%