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The United States military is researching the use of nanocomposite materials for structural applications on space vehicle systems. To reduce vehicle weight and mitigate the electromagnetic interference (EMI) brought on by the harsh space environment, today's space vehicles are made of composites coated with expensive conductive materials. Research on composites made of carbon nanotubes (CNT) and carbon nanofibers (CNF) has shown better EMI shielding performance with these materials compared to the current composites coated with expensive conductive materials. Thus, CNTs and CNFs offer the potential to replace the current composites. This study evaluated the effects of EMI behavior on one control composite (i.e., without nanocomposite) and five different configured nanocomposites under fatigue. The control specimen, 8G, consisted of eight plies S-glass (Astroquartz II) fiber in CYCOM 5575-2 cyanate ester matrix. The first nanocomposite, 8G/CNT, consisted of eight plies of 6781 S-2 glass fiber in CYCOM 5250-4 Bismaleimide (BMI) matrix with an externally deposited layer of CNTs. The second nanocomposite, 8G/CNF, consisted of eight plies of 6781 S-2 glass fiber in CYCOM 5250-4 BMI matrix with an externally deposited layer of CNFs. The last three nanocomposites, (G/CNT)4, 2CNT/4G/2CNT, and 4G/4CNT, consisted of different stacking sequences of multi-wall CNTs (MWNT) with S-glass (Astroquartz II) fiber in CYCOM 5575-2 cyanate ester matrix.

© Almohalla et al.; Licensee Bentham Open ; Catalytic bioethanol transformations over carbon nanomaterials (nanofibers and nanotubes) have been evaluated at atmospheric pressure and in the temperature range of 473-773 K. The pristine carbon materials were compared with these samples after surface modification by introducing sulfonic groups. The specific activity for ethanol dehydrogenation, yielding acetaldehyde, increases with the surface graphitization degree for these materials. This suggests that some basic sites can be related with specific surface graphitic structures or with the conjugated basic sites produced after removing acidic oxygen surface groups. Concerning the dehydration reaction over sulfonated samples, it is observed that catalytic activities are related with the amount of incorporated sulfur species, as detected by the evolution of SO2 in the Temperature programmed Desorption (TPD) as well as by the analysis of sulfur by X-Ray Photoelectron Spectroscopy (XPS). ; The financial support of the Spanish government by Projects CTQ2011-29272-C04-01 and 03 is recognized. ; Peer Reviewed

First published online Jan. 16, 2012 ; A well attached coating of nitrogen-functionalised carbon nanofibers (N-CNFs) has been prepared on the walls of cordierite monolith channels. It is formed via concurrent decomposition of ethane and ammonia catalysed by nickel nanoparticles dispersed on alumina coated cordierite monolith. N-CNF/monoliths synthesis employing several growth temperatures and NH 3 compositions was exhaustively characterised by Raman, XPS, elemental analysis and TEM. Synthesis conditions affected profoundly content and type of nitrogen functionality, enabling its fine tuning. N-CNFs surface chemistry and microstructure differed remarkably from its N-free counterparts. ; The authors are grateful to the financial support of the European Commission within the 7th FP (Grant agreement no.: 226347) and of Spanish Government (MAT 2008-02365). ; Peer Reviewed

Carbon materials have rarely been used as support for CO2 methanation, which is usually carried out using catalysts supported on metal oxides. Here, it is shown that Ru nanoparticles supported on nitrogen-doped carbon nanofibers (NCNF) provide competitive CH4 production rate and stability compared to Al2O3-supported catalysts. Contrary to the general belief about the inert nature of carbon supports, it is demonstrated that NCNF is a non-innocent spectator in CO2 methanation due to its ability to store a high amount of COad reaction intermediates. This explains the excellent catalytic behaviour afforded by this unconventional catalyst support. ; The financial support of European Commission (FREECATS project, FP7 Grant agreement nº 280658), from Spanish Ministry MINECO and the European Regional Development Fund (project ENE2013-48816-C5-5-R), and Regional Government of Aragon (DGA-ESF-T66 Grupo Consolidado) are gratefully acknowledged. ; Peer reviewed

16 figures, 6 tables.-- Supplementary material available. ; Ceria-iron oxide mesoporous materials with Fe:Ce molar ratio of 5:5 and 9:1 were synthesized by hydrothermal method using CTAB as a template and subsequently modified with NiO (molar ratio Ni:Fe = 1:2) by incipient wetness impregnation technique. In order to increase the electro-capacitive properties and reduce the intrinsic impedance of the metal oxides, the samples were consecutively modified by reduction in hydrogen to obtain highly dispersed Ni–Fe alloys into ceria matrix. By exploiting the high permeability of carbon inside ferrous alloys, the metal phase has been further modified into ferrous carbides and metal alloys encapsulated within carbon nanofibers. For this purpose, a reaction, already widely studied for the production of hydrogen, was used, that is the decomposition of methanol vapors. In fact, this decomposition, in addition to producing syn-gas and methane, changes the catalysts in use through a chemical vapor deposition-carbon coating process. This fact, has been used by us to demonstrate how the newly obtained metal-carbon nanocomposites can be used for electro-catalytic purposes. The modified phases of the two molar ratios of the Fe–Ni–Ce catalysts were tested in the Oxygen Evolution Reaction (OER) in an alkaline environment (1 M KOH), showing a satisfactory and progressive increase in activity and a surprising decrease in the overpotential at 10 mA/cm2 of current density. The morphological, textural and physicochemical properties of the samples were characterized in details by XRD, N2-physisorption, TG-TPO, TEM, EDX, FTIR, XPS, Raman and Moessbauer spectroscopies. ; This research was funded by the BIKE project, which received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 813748. ; Peer reviewed

Catalytic CO2 reduction has been performed using carbon nanofibers or nitrogen doped carbon nanofibers as novel support for several Ru contents. The catalyst consisting of 5 wt% Ru on nitrogen doped carbon nanofiber exhibited the highest conversion at relatively low temperature, complete selectivity to CH4 and stable catalytic performance. The catalytic performance was substantially superior to catalysts supported on carbon nanotubes and akin to the best metal oxide supported catalyst in the literature. The characterisation of the prepared catalyst by transient experiments (CO2-TPD, TPSR and transient response to CO2 removal) revealed that the catalyst support participates actively in the reaction. The Ru content governed the selectivity, either favouring CO formation for lower Ru contents (0.5-2 wt%) or CH4 formation for 5 wt% Ru loading. The mean Ru particle size determined by TEM was similar for the several metal loadings. Therefore, the substantially different selectivity patterns cannot be attributed to structure sensitivity. The higher selectivity to CH4 can be explained by the enhanced supply of 4 Had to the activated COad intermediate, which was demonstrated to be the rate determining step. ; The financial support of European Commission (FREECATS project, FP7 Grant agreement nº 280658) from Spanish Ministry MINECO and the European Regional Development Fund (project ENE2013-48816-C5-5-R), and Regional Government of Aragon (DGA-ESF-T66 Grupo Consolidado) are gratefully acknowledged. ; Peer reviewed