A laser Raman spectroscopy study of molybdenum oxide supported on alumina and titania

Arco, M. Del; Carrazán, S.R.G.; Martı́n, Cristina; Rives, V.; Garcı́a-Ramos, José Vicente; Carmona, Pedro

doi:10.1016/0584-8539(93)e0029-v

Cited by 16 publications

(6 citation statements)

References 20 publications

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“…However, there are no other distinct α-MoO 3 -like bands in the TiO 2 -(MoO 3 ) x Raman data, which indicates the shell does not possess any long-range crystalline order. Previous Raman studies on dispersed molybdenum oxide compounds have shown the presence of polymolybdate and pentacoordinate molybdate surface species. − However, in contrast to our materials, they found the structural nature of their surface molybdenum oxide species to be highly dependent on the concentration of molybdenum oxide present and whether the samples were hydrated (i.e. exposed to ambient air) or dehydrated.…”

Section: Resultscontrasting

confidence: 85%

The Discovery and Study of Nanocrystalline TiO₂-(MoO₃) Core−Shell Materials

et al. 2000

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Here we report the synthesis of a series of new nanocrystalline TiO2-(MoO3) core−shell materials whose photoabsorption energy (PE, the energy required to excite TiO2-core valence band electrons to MoO3-shell conduction band states) properties are correlated with both the nanoparticle size and the degree of chemical interaction between the TiO2 core and the MoO3 shell. The TiO2-(MoO3) nanoparticle size can be readily adjusted from 80 to 40 Å, and in this series, the PE decreases from 2.88 to 2.60 eV with decreasing particle size. The systematic PE red-shift exhibited by the core−shell materials is ascribed to the change in the relative position of the MoO3-shell conduction band as it evolves from less than a monolayer to a two monolayer shell.

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Section: Resultscontrasting

confidence: 85%

The Discovery and Study of Nanocrystalline TiO₂-(MoO₃) Core−Shell Materials

et al. 2000

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“…The CB consists mainly of Ti 3d states with a smaller contribution from the O 2p states, which show two distinct structures . Consistent with the earlier literature, molybdenum oxide species may be generally dispersed on metal oxide supports due to strong X–O–Mo (X = Ti, Zr, Al, and Si) bonding. − There was generally a mismatch between the a , c unit cell axes of MoO 3 and the a unit cell axis of anatase. , Therefore, it is quite reasonable to believe that MoO 3 could have been nucleated on the surface of anatase TiO 2 nanocrystals to produce a nano hetero composite along with the partial doping of Mo in the TiO 2 lattice. It may be assumed that changes in band gap properties of the Mo–TiO 2 system are basically due to charge-transfer processes at the semiconductor heterojunction formed between the MoO 3 and the anatase TiO 2 .…”

Section: Resultssupporting

confidence: 73%

Effect of Mo-Incorporation in the TiO₂ Lattice: A Mechanistic Basis for Photocatalytic Dye Degradation

et al. 2014

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Photocatalytic activity of TiO 2 (anatase) is appreciably enhanced by substitutional doping of Mo in anatase lattice, in conjunction with the incorporation of nanostructured MoO 3 within the parent anatase lattice. The photocatalyst material was characterized in detail using X-ray diffraction, Raman spectroscopy, diffuse reflectance (DR-UV− Vis spectroscopy), X-ray photoelectron spectroscopy, and electron microscopy. Photocatalysis experiments were conducted using a model rhodamine-B (Rh−B) dye reaction using both UV and visible irradiation sources. The observed trends in the case of visible irradiative source can be summarized as follows: Mo-1 < Mo-2 < Mo-5 ≫ Mo-10. Attempts were made to isolate the structural factors that control photochemical behavior of these Mo−TiO 2 photocatalysts and to correlate photocatalytic activity with different structural aspects like oxidation state, band gap, surface species, etc. Mechanistic insights were acquired from ex situ 1 H NMR studies showing different intermediates and different probable routes for the Rh−B dye degradation with UV and visible radiations. The stable intermediates were formed by a direct oxidative fragmentation route, without any evidence of the initial deethylation route. The intermediates found were benzoic acid, different amines, diols, and certain acids (mostly formic and acetic acid). The adsorption of the Rh−B dye on the catalytic surface via the N-charge centers of the Rh−B was also observed.

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“…All of these observations support the earlier hypothesis that the nanosheets are rutile TiO 2 with exposed (001) facets that are stabilized by amorphous MoO 3 . Indeed, several previous reports have proved that MoO 3 has a high tendency to be dispersed onto the surface of other oxide materials, including SiO 2 , Al 2 O 3 and TiO 2 , [28][29][30] showing the strongest interactions with titania supports. 30 It is thus conceivable that the amorphous MoO 3 forms bonds with the highly reactive (001) surfaces of rutile TiO 2 , which provides the enhanced stabilities of these high-energy facets.…”

Section: Resultsmentioning

confidence: 99%

Unusual rutile TiO2 nanosheets with exposed (001) facets

Chen

Lou

2011

Chem. Sci.

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In this work, we report an interesting synthesis of unusual rutile TiO 2 nanosheets with exposed highenergy (001) facets, which form hierarchical microspheres that closely resemble the natural ''desert rose''. These high-energy (001) surfaces are stabilized by amorphous molybdenum trioxide (MoO 3 ), which is homogeneously dispersed on the TiO 2 nanosheets. The as-prepared unique TiO 2 -MoO 3 hybrid structure exhibits improved lithium storage capabilities.

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A laser Raman spectroscopy study of molybdenum oxide supported on alumina and titania

Cited by 16 publications

References 20 publications

The Discovery and Study of Nanocrystalline TiO₂-(MoO₃) Core−Shell Materials

The Discovery and Study of Nanocrystalline TiO₂-(MoO₃) Core−Shell Materials

Effect of Mo-Incorporation in the TiO₂ Lattice: A Mechanistic Basis for Photocatalytic Dye Degradation

Unusual rutile TiO2 nanosheets with exposed (001) facets

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A laser Raman spectroscopy study of molybdenum oxide supported on alumina and titania

Cited by 16 publications

References 20 publications

The Discovery and Study of Nanocrystalline TiO2-(MoO3) Core−Shell Materials

The Discovery and Study of Nanocrystalline TiO2-(MoO3) Core−Shell Materials

Effect of Mo-Incorporation in the TiO2 Lattice: A Mechanistic Basis for Photocatalytic Dye Degradation

Unusual rutile TiO2 nanosheets with exposed (001) facets

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The Discovery and Study of Nanocrystalline TiO₂-(MoO₃) Core−Shell Materials

The Discovery and Study of Nanocrystalline TiO₂-(MoO₃) Core−Shell Materials

Effect of Mo-Incorporation in the TiO₂ Lattice: A Mechanistic Basis for Photocatalytic Dye Degradation