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, et al.. Electrical properties and reactivity under air-CO flows of composite systems based on ceria coated carbon nanotubes. Chemical Engineering Journal, Elsevier, 2011Elsevier, , vol. 171, pp. 272-278. 10.1016Elsevier, /j.cej.2011 This is an author-deposited version published in: http://oatao.univ-toulouse.fr/ Eprints ID: 8690 OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.Any correspondence concerning this service should be sent to the repository administrator: staff-oatao@listes-diff.inp-toulouse.fr Nanocomposite systems of ceria nanoparticles and Double Walled Carbon Nanotubes (DWNTs) coated with nano-ceria (n-CeO 2 ) were elaborated using a classical sol gel method. Three samples noted as [n-CeO 2 + xDWNTs] with variable weight fractions x = 0, 5 and 15 wt.% of DWNTs were obtained. The samples were characterized by X-ray diffraction and electron microscopy. The electrical conductivity of [n-CeO 2 + xDWNTs] compacted pellets systems was determined from electrical impedance spectrometry, under air, between 120 and 400• C. In this temperature range, all samples were semi-conducting with a weak variation of activation energy. However, the conductivity strongly increased with the weight fraction of ceria coated carbon nanotubes. Finally, the solid-gas interactions between air-CO flows and these systems were studied as a function of time and temperature, by means of Fourier transform infrared (FTIR) spectroscopy. The oxidation kinetics of CO into CO 2 was analyzed from the evolutions of FTIR absorption band intensities. As the carbon nanotube fraction x increased, the conversion efficiency was strongly improved.

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Carbon nanotubes flower (CNTs-F) films were prepared by catalytic chemical vapor deposition (CVD) on a platinum (Pt) thin layer, supported on a silicon wafer. The products were synthesized from an aerosol composed of ferrocene and toluene, as catalyst and carbon precursor respectively, at 820. The high synthesis temperature induces a modification of a Pt thin layer to a nano-structured island giving rise to the formation of CNTs-F during the following films growth step by CVD process. The suggested mechanism involves the selective diffusion of the catalyst and carbon atoms through the Pt grain boundaries. This results in the appearance of flower-like structures with 3-and 4-fold symmetries.