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The redox properties of furnace-type carbon blacks were studied by UV-visible spectrophotometry and potentiometry. The carbon black surface was exposed to redox reagents such as Cr(VI), Mn(VII), Fe(III), and sulfite. The ability of the carbon black surface to undergo redox reactions with these reagents was correlated with the morphological attributes of the black such as crystallite size and surface...
We report here the preparation of Kevlar-derived carbon fibers and the preliminary results on their anodic performances in Li secondary batteries. The single- or two-step carbonization process is employed for the preparation. In the single-step process, the Kevlar flocks are heat-treated under Ar atmosphere from 25 to 800 o C with a heating rate of 5 o C min -1 , but an...
The direct conversion of electrical energy into mechanical energy is crucial for a number of high-technology applications. Macroscopic sheets of single-walled carbon nanotubes, working under physiological conditions (in salt water for example) and low voltage, have shown comparable or superior performances than natural muscle. Specific characteristics of single or nanotube bundles allows one to expect...
The evolution of the electrochemical double layer capacitance of glassy carbon during thermochemical gas phase oxidation was studied with electrochemical impedance spectroscopy. Particular attention was paid to the initial oxidation stage, during which the capacitance grows exponentially. This stage could be experimentally assessed by lowering the reaction temperature and oxidant partial pressure...
Group 15 element–graphite M/C composites were prepared by reduction of MCl x chlorides (AsCl 3 , SbCl 5 , BiCl 3 ) by KC 8 in THF. Arsenic and antimony were both amorphous: antimony appeared as a film-like material, formed of aggregated nano-sized particles covering parts of the graphite surface; arsenic was present as large graphite supported particles. On...
Highly ordered porous carbon materials obtained by a replica technique have been used for supercapacitor application and electrochemical hydrogen storage. For the preparation of the well-tailored carbons, MCM-48, SBA-15 and MSU-1 molecular sieves served as templates, whereas a sucrose solution, propylene and pitch were the carbon source. A careful physico-chemical characterization (CO 2 and...
Silver (Ag) nanoparticles were electrocrystallized on 4-aminobenzene monolayer-grafted multi-walled carbon nanotubes (MWNTs) by a potential-step method. The structure and nature of the resulting Ag/MWNT composite were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD), the results show that the electrochemically synthesized Ag nanoparticles were homogeneously dispersed...
A large specific surface area (SSA) of carbon materials used for electrochemical double layer capacitors (EDLC) is the most important parameter leading to a large gravimetric capacitance (C g ). However, for a SSA determined with the differential functional theory (DFT) model above a value of 1200m 2 /g the plot of C g versus S DFT exhibits a plateau. We suggest that...
1-Ethyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide (EMI-TFSI) is shown to reversibly permit lithium intercalation into standard TIMREX ® SFG44 graphite when vinylene carbonate (VC) is used in small amounts as additive. The best performance was obtained when 5% of VC was added to a 1M solution of LiPF 6 in EMI-TFSI. Intercalation of lithium in the SFG44 graphite host was...
Porous mats of carbon nanotubes, referred to as bucky paper, are becoming a viable engineering material, especially as electrodes in numerous types of electrochemical cells. The tensile strength of bucky paper was measured in the dry atmospheric condition, and the wet conditions of both water and 1-butyl-3-methyl-imidazolium tetrafluoroborate, an ionic liquid. The two different liquids have a significant...
The preparation and aqueous electrochemistry of carbon paste electrodes modified by single wall carbon nanotubes and C 60 are reported. The matrix of carbon corresponds to an experimental turbostratic carbon black with low surface area. In all cases, the redox reactions studied by Cyclic Voltammetry in 6M KOH can be assigned to the reduction/oxidation of intrinsic carbon–oxygen complexes and...
Negative electrodes of lithium–ion batteries are generally based on graphite. Higher storage capacities can be obtained with disordered carbons, however they demonstrate a noticeable hysteresis and irreversibility, which can preclude a practical application. In this paper, the main parameters which may affect the irreversible capacity are analyzed and we show that the irreversible lithium consumption...
Pt nanoparticles with different mean sizes supported on carbon nanotubes were synthesized by microwave heating ethylene glycol solutions of platinum salt with different pH in present of CNTs as supports. TEM examinations showed that Pt particles become smaller and more uniform when the synthesis pH increased from 3.4 to 9.2. The mean particle size was 5.8, 5.2, 3.4 and 2.7nm when the synthesis pH...
Intercalation of metal chlorides into fine natural graphite flakes of 2×10 −6 m in diameter was attempted. CuCl 2 was satisfactorily intercalated from the vapour phase. NiCl 2 and PdCl 2 were also intercalated from the liquid phase using chloroform solvent. The reduction products of the obtained graphite intercalation compounds were used as carbon supports of the platinum...
Ordered microporous carbon with a structure of amorphous carbon core and graphitic carbon shell was prepared using hydrogen-form zeolite Y as the template. Impregnation and chemical vapor deposition methods were employed to infiltrate carbon in the pores of the template. Physical adsorption of nitrogen, X-ray diffraction, thermogravimetric analysis, field-emission scanning electron microscope, and...
For the purpose of obtaining an improved performance of the graphite negative electrode of Li-ion batteries, a novel graphite–tin composite has been synthesized by reduction of tin chloride (SnCl 2 ) with KC 8 in THF medium. This composite contains nano-sized tin particles dispersed on the graphite surface and free tin aggregates. Lithium electrochemical insertion occurs both in graphite...
Vulcan XC-72 carbon black particles (average size: ca. 50nm) was incorporated into polyaniline (PANI) matrix by an electrochemical codeposition technique during the electropolymerization process. The doping by carbon particles leads to a higher polymeric degree and a lower defect density in the PANI structure. Furthermore, the incorporation of carbon particles not only increases the electrochemical...
Aniline/o-anisidine copolymer (P(An-co-oAs))-intercalated GO composite was synthesized by the delamination/reassembling method in N-methyl-2-pyrrolidone (NMP) solvent, and was characterized by FTIR, XRD, DSC, SEM, TGA, conductivity and cyclic voltammetry. XRD and FTIR spectra indicate that the P(An-co-oAs) exists as a monolayer of outstretched chains in the gallery of GO due to the hydrogen bonds...
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