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Increased chemical reactivity of single-walled carbon nanotubes on oxide substrates: In situ imaging and effect of electron and laser irradiations
Auteur(s): Mehedi Hasan-Al, Ravaux Johann, Yazda K., Michel T., Tahir S., Odorico Michaël, Podor Renaud, Jourdain V.
(Article) Publié:
Nano Research, vol. 9 p.517-529 (2016)
Ref HAL: hal-01304896_v1
DOI: 10.1007/s12274-015-0933-5
WoS: WOS:000371798800024
Exporter : BibTex | endNote
6 Citations
Résumé: We studied the oxygen etching of individual single-walled carbon nanotubes on silicon oxide substrates using atomic force microscopy and high-temperature environmental scanning electron microscopy. Our in situ observations show that carbon nanotubes are not progressively etched from their ends, as frequently assumed, but disappear segment by segment. Atomic force microscopy, before and after oxidation, reveals that the oxidation of carbon nanotubes on substrates proceeds through a local cutting that is followed by a rapid etching of the disconnected nanotube segment. Unexpectedly, semiconducting nanotubes appear more reactive under these conditions than metallic ones. We also show that exposure to electron and laser beams locally increases the chemical reactivity of carbon nanotubes on such substrates. These results are rationalized by considering the effect of substrate-trapped charges on the nanotube density of states close to the Fermi level, which is impacted by the substrate type and the exposure to electron and laser beams.
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Eu 3+ -Based Bridged Silsesquioxanes for Transparent Luminescent Solar Concentrators
Auteur(s): Freitas Vânia., Fu Lianshe, Cojocariu Ana, Cattoën Xavier, Bartlett John, Le Parc R., Bantignies J.-L., Wong Chi Man Michel, André Paulo, Ferreira Rute, Carlos Luis
(Article) Publié:
Acs Appl. Mater. Interfaces, vol. 7 p.8770-8778 (2015)
Ref HAL: hal-02392070_v1
DOI: 10.1021/acsami.5b01281
WoS: 000353931300048
Exporter : BibTex | endNote
59 Citations
Résumé: The sol−gel preparation of a bridged silsesquioxane containingeuropium(III) salts and 2-thenoyltrifluoroacetone has been achieved from a newethane tetracarboxamide-based organosilane. Free-standing films with thicknessesup to 440 μm and maximum absolute quantum yield (q) of 0.34 ± 0.03(excitation at 320 nm) were prepared by the drop cast method, while thin films(∼200−400 nm) spin-coated on glass substrates led to highly luminescentcoatings with q = 0.60 ± 0.02 (excitation at 345 nm). The thin films were testedas planar luminescent solar concentrators and the optimized device displays anoptical conversion efficiency of 12.3% in the absorbing spectral region of theactive layer (300−380 nm).
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Turning Peptide Sequences into Ribbon Foldamers by a Straightforward Multicyclization Reaction
Auteur(s): Martin Vincent, Legrand Baptiste, Vezenkov Lubomir, Berthet Mathéo, Subra Gilles, Calmes Monique, Bantignies J.-L., Martinez Jean, Amblard Muriel
(Article) Publié:
Angewandte Chemie International Edition, vol. 54 p.13966-13970 (2015)
Texte intégral en Openaccess :
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Evaporation-Induced Self-Structuring of Organised Silica Nanohybrid Films Through Cooperative Physical and Chemical Interactions
Auteur(s): Cojocariu Ana M., Cattoën Xavier, Le Parc R., Maurin D., Blanc C., Dieudonne-George P., Bantignies J.-L., Wong Chi Man Michel, Bartlett John R.
(Article) Publié:
Physical Chemistry Chemical Physics, vol. 18 p.7946 (2016)
Ref HAL: hal-01279551_v1
DOI: 10.1039/C5CP02742J
WoS: 000372229700039
Exporter : BibTex | endNote
4 Citations
Résumé: In this work, we develop the concept of evaporation-induced self-structuring as a novel approach forproducing organised films by exploiting cooperative physical and chemical interactions under far-fromequilibriumconditions (spin-coating), using sol–gel precursors with multiple functional groups. Thin filmsof self-structured silsesquioxane nanohybrids have been deposited by spin coating through the sol–gelhydrolysis and condensation of a bridged organosilane bearing self-assembling urea groups. The resultingnanostructure, investigated by FTIR, AFM and SEM, is shown to be highly dependent on the catalyst used(nucleophilic or acidic), and can be further modulated by varying the spinning rate. FTIR studies revealed thepresence of highly organised structures under acidic catalysis due to strong hydrogen bonding between ureagroups and hydrophobic interactions between long alkylene chains. The preferential orientation of the ureacross-links parallel to the substrate is shown using polarized FTIR experiments.
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Interlayer Dependence of G-Modes in Semiconducting Double-Walled Carbon Nanotubes
Auteur(s): Levshov D., Michel T., Arenal Raul, Tran H.-N., Than X. T., Paillet M., Yukzuk Yuri, Sauvajol J.-L.
(Article) Publié:
The Journal Of Physical Chemistry C, vol. 119 p.23196-23202 (2015)
Texte intégral en Openaccess :
Ref HAL: hal-01243524_v1
DOI: 10.1021/acs.jpcc.5b05888
WoS: WOS:000362702100050
Exporter : BibTex | endNote
19 Citations
Résumé: A double-walled carbon nanotube (DWNT), a coaxial composite of two single walled carbon nanotubes (SWNT), provides a unique model to study interactions between thetwo constituent SWNTs. Combining high resolution transmission electron microscopy (HRTEM), electron diffraction (ED), and resonant Raman scattering (RRS) experiments on the same individual suspended DWNT is the ultimate way to relate unambiguously its atomicstructure, defined by the chiral indices of the coaxial outer/inner SWNTs, and its Raman-active vibration modes. This approach is used to investigate the intertube distance dependence of theG-modes of individual index-identified DWNTs composed of two semiconducting SWNTs.We state the main features of the dependence of the G-mode frequencies on the distance between the inner and outer layers: (i) When the interlayer distance is larger than the nominal van der Waals distance (close to 0.34 nm), a downshift of the inner-layer G-modes with respectto the G-modes in the equivalent SWNTs is measured. (ii) The amplitude of the downshiftdepends on the interlayer distance, or in other words, on the negative pressure felt by the innerlayer in DWNT. (iii) No shift is observed for an intertube distance close to 0.34 nm.
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Influence of packing on the vibrations of homogeneous bundles of C-60 peapods
Auteur(s): Chadli H., Fergani F., Bentaleb M., Fakrach B., Sbai K., Rahmani A., Bantignies J.-L., Sauvajol J.-L.
(Article) Publié:
Physica E: Low-Dimensional Systems And Nanostructures, vol. 71 p.31-38 (2015)
Ref HAL: hal-01202120_v1
DOI: 10.1016/j.physe.2015.03.018
WoS: WOS:000354097300005
Exporter : BibTex | endNote
5 Citations
Résumé: The non-resonant Raman spectra of homogeneous bundles of C60 peapods (C60 inserted in single-walled carbon nanotubes) are calculated in the framework of spectral moment method, together with a bond-polarizability model. The evolutions of the low wavenumber range of the Raman spectrum of homogeneous bundles of C60 peapods as a function of the nanotube diameter and the size of bundles are discussed. The effect of the C60 filling factor is investigated in detail. The results are compared to experimental Raman data measured on various samples of C60 peapods.
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AlPO4-54-AlPO4-8 Structural Phase Transition and Amorphization under High Pressure
Auteur(s): Alabarse Frederico, Brubach Jean-Blaise, Roy Pascale, Haidoux Abel, Levelut C., Bantignies J.-L., Cambon Olivier, Haines Julien
(Article) Publié:
The Journal Of Physical Chemistry C, vol. 119 p.7771-7779 (2015)
Ref HAL: hal-01202111_v1
DOI: 10.1021/acs.jpcc.5b00318
WoS: WOS:000352823300025
Exporter : BibTex | endNote
14 Citations
Résumé: Microporous AlPO4-54, which exhibits the largest pores among zeolites and aluminophosphates with a diameter of 12.7 Å, was investigated at high pressure by X-ray powder diffraction (XRD), mid- and far-infrared (IR) spectroscopy in diamond anvil cells. The material undergoes a phase transition beginning around 0.8 GPa. The amount of AlPO4-8 gradually increases with pressure and the phase transition is complete between 2 and 3 GPa. The closure of the (P—O—Al) angle destabilizes the structure of AlPO4-54, which drives the transition to AlPO4-8. The pressure-induced phase transformation of AlPO4-54 to AlPO4-8 is associated with a symmetry reduction from hexagonal to orthorhombic and with a change in the unidirectional ring channel parallel to the c-axes from 18 to 14 AlO4 and PO4 tetrahedra. An abrupt decrease along the b direction is linked to the formation of 4 new rings of 6 tetrahedra with significant structural reorganization. The transition is followed by irreversible amorphization beginning around 3.5 GPa due to the collapse of the pores. The amorphization of AlPO4-8 was detected from the disappearance of the XRD lines, abrupt shifts, and strong broadening of the mid-IR modes, and by changes in the pressure dependence of the mid- and far-IR modes, indicating a lower compressibility for the more dense amorphous form. Far-IR spectra indicate that the new amorphous form retains the local structure of AlPO4-8.
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