References of "Colomer, Jean-Francois"
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See detailSynthesis of titanium dioxide nanoparticles by reactive DC magnetron sputtering
Dreesen, Laurent ULg; Colomer, Jean-François; Limage, Hervé et al

in Thin Solid Films (2009), 518

Nanometer-sized titanium dioxide (TiO2) particles were prepared on carbon substrates by reactive direct-current magnetron sputtering. By performing measurements with high resolution electron microscopes ... [more ▼]

Nanometer-sized titanium dioxide (TiO2) particles were prepared on carbon substrates by reactive direct-current magnetron sputtering. By performing measurements with high resolution electron microscopes, the mean nanoparticle diameter and the coverage fraction of the substrate by the nanoparticles (NPs) were measured at 19 nm and 30%, respectively. Moreover, electron diffraction analysis showed that the TiO2 NPs' crystalline structure on the carbon substrate was a mixture of anatase and rutile. Finally,we provided information on the TiO2 initial growth stage: crystalline NPs were formed after deposition of amorphous nanoparticles on the substrate and heating. [less ▲]

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See detailCarbon nanotubes synthesis by the ethylene chemical catalytic vapour deposition (CCVD) process on Fe, Co, and Fe-Co/Al2O3 sol-gel catalysts
Tran, Kim Yên; Heinrichs, Benoît ULg; Colomer, Jean-François et al

in Applied Catalysis A : General (2007), 318

The production of carbon nanotubes by the chemical catalytic vapour deposition, CCVD, process was examined over iron, cobalt, and a mixture of iron and cobalt supported on alumina catalysts synthesized by ... [more ▼]

The production of carbon nanotubes by the chemical catalytic vapour deposition, CCVD, process was examined over iron, cobalt, and a mixture of iron and cobalt supported on alumina catalysts synthesized by a one step sol-gel process. The catalysts were synthesized from several metal precursors, iron nitrate, cobalt and iron acetylacetonate, and cobalt acetate. Ethylene was used as the carbon source. The Co/Al2O3 catalysts showed better activity and selectivity in carbon nanotubes synthesis than Fe/Al2O3 and Fe-Co/Al2O3 catalysts. The carbon deposit was found by TEM analysis to be rich in carbon nanotubes in the case of Co/Al2O3 but to be very poor in the case of the Fe-Co/Al2O3 catalysts. The catalysts were characterized by TEM, XRD, and nitrogen adsorption. It was shown that iron and cobalt are in oxide form. Metal-support interactions and metal oxide particle size are influenced by the nature of the precursor and this nature is an important factor for the activity and selectivity of the catalysts. Moreover, a correlation has been found between the metal oxide particle sizes, the diameter of the carbon nanotubes, and the catalytic activity. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]

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See detailSynthesis of transition metal-doped carbon xerogels by cogelation
Job, Nathalie ULg; Pirard, René ULg; Vertruyen, Bénédicte ULg et al

in Journal of Non-Crystalline Solids (2007), 353(24-25), 2333-2345

The cogelation process, i.e. the co-polymerization of a metal complex with the gel precursors, was used for the synthesis of transition metal-doped resorcinol-formaldehyde gels. The aim of this process is ... [more ▼]

The cogelation process, i.e. the co-polymerization of a metal complex with the gel precursors, was used for the synthesis of transition metal-doped resorcinol-formaldehyde gels. The aim of this process is to anchor the metal to the polymer so that the former does not sinter during the pyrolysis step leading to porous carbon. Cu-, Ni-, Pd- or Pt-loaded gels were prepared by this technique. After drying and pyrolysis, Pd and Pt were obtained as metal nanoparticles (2-5 nm in diameter) inserted in the carbon nodules, when the complexing agent and the synthesis conditions were well chosen. These small metal particles were inaccessible to reactive gases, probably due to carbon deposit at the metal surface during pyrolysis: CO almost did not chemisorb. Oxidation of the support or pyrolysis under reductive atmosphere was applied to the metal-doped gels and carbons in order to make the surface of the metal particles accessible, but these treatments develop the macropores only. The cogelation process is then suitable to prepare metal nanoparticles protected from the outside by encapsulation in the carbon matrix. (C) 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailMetal catalysts suppported on texture-tailored carbon xerogels
Job, Nathalie ULg; Léonard, Angélique ULg; Colomer, Jean-François et al

in Studies in Surface Science and Catalysis (2006), 162

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See detailHighly dispersed platinum catalysts prepared by impregnation of texture-tailored carbon xerogels
Job, Nathalie ULg; Ribeiro Pereira, Manuel Fernando; Lambert, Stéphanie ULg et al

in Journal of Catalysis (2006), 240(2), 160-171

Pt/C catalysts were prepared by impregnation of carbon xerogels with H2PtCl6 aqueous solutions. Three supports with various pore textures were used: two micro-mesoporous (maximum pore size = 10 and 40 nm ... [more ▼]

Pt/C catalysts were prepared by impregnation of carbon xerogels with H2PtCl6 aqueous solutions. Three supports with various pore textures were used: two micro-mesoporous (maximum pore size = 10 and 40 nm, respectively) and one micro-macroporous (maximum pore size = 70 nm). After impregnation, drying and reduction, the metal particles were at most 1-1.5 nm in diameter. The Pt dispersion was close to 100% in the case of the xerogel with large mesopores. For the two other supports, a small fraction of Pt was trapped in blocked micropores. The specific catalytic activity obtained for benzene hydrogenation was 4-10 times higher than that obtained with active charcoal-supported catalysts prepared by a similar method. The high dispersion of Pt was attributed to the presence in the xerogel of large mesopore or macropore volumes, which facilitates impregnation, and a low amount of oxygenated surface groups. (c) 2006 Elsevier Inc. All rights reserved. [less ▲]

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See detailCarbon xerogels as catalyst supports: study of mass transfer
Job, Nathalie ULg; Heinrichs, Benoît ULg; Lambert, Stéphanie ULg et al

in AIChE Journal (2006), 52

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See detailBall milling effect on the structure of single-wall carbon nanotubes
Pierard, N.; Fonseca, Antonio; Colomer, Jean-François et al

in Carbon (2004), 42(8-9), 1691-1697

The vibratory mill is used to decrease the single-wall carbon nanotubes (SWNTs) length and to increase their specific surface area. Electron microscopy, Raman spectroscopy, X-ray diffraction and BET ... [more ▼]

The vibratory mill is used to decrease the single-wall carbon nanotubes (SWNTs) length and to increase their specific surface area. Electron microscopy, Raman spectroscopy, X-ray diffraction and BET measurements indicated that the optimum time of treatment seems to be 2 h. After that, the SWNTs quality decreases, with a complete disruption of the tubular structure leading to multi-layered polyaromatic carbon materials observed after 50 h. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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