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The nonlinear optical properties of linear carbon chains prepared by laser ablation in water were studied by using a nanosecond pulsed excitation. A strong optical limiting response was detected at laser fluences above 0.6J/cm2. The nature of the nonlinear effect was investigated by the Z-scan technique, determining both the nonlinear absorption coefficient β and the refraction one n2. A high second-order...
The fabrication and characterization of ultrathin composite films of surfactant-wrapped graphene nanoflakes and poly(vinyl chloride) is described. Free-standing composite thin films were prepared by a simple solution blending, drop casting and annealing route. A significant enhancement in the mechanical properties of pure poly(vinyl chloride) films was obtained with a 2wt.% loading of graphene, such...
An easy co-gelation route has been developed to synthesize porous graphitic carbons with high surface areas by using teraethylorthosilicate (TEOS), furfuryl alcohol (FA), and metal nitrates as precursors. Using a one-pot co-gelation process, a polyfurfuryl alcohol–silica interpenetrating framework with metal ions uniformly dispersed was formed during the polymerization of FA and the hydrolysis of...
Carbon nanospheres (CNSs) with the diameters of 50–250nm were synthesized through a one-step solvothermal method at about 300°C. In this process, benzene and hexachloroethane (C 2 Cl 6 ) served as carbon source for the CNSs. The results showed that the CNSs were composed of a mixture of graphitic nanocrystallites and amorphous carbon. It is believed that they formed through intermolecular...
A flexible, transparent heater was manufactured by spinning multi-walled carbon nanotubes (MWCNTs). MWCNT sheets were produced by continuously pulling on well-aligned MWCNTs, and films were produced by directly coating a flexible film. Single and double sheets were produced with sheet resistances of ∼699Ω/sq and ∼349Ω/sq and transmittances of 81% to 85% and 67% to 72%, respectively. Both films were...
Large area (the order of centimeters), flexible thin films of amorphous carbon were prepared on copper foils by an ethanol flame synthesis method. The carbon films exhibit high transmittance in the visible and near infrared range (up to 90% at 550nm). Schottky diodes formed by combining the carbon films with n-type silicon wafers show high on/off ratio (up to 150) photocurrents at air-mass 1.5 and...
Six commonly used wet chemical oxidants (HNO 3 , KMnO 4 , H 2 SO 4 /HNO 3 , (NH 4 ) 2 S 2 O 8 , H 2 O 2 , and O 3 ) were evaluated in terms of their effects on the surface chemistry and structure of MWCNTs using a combination of analytical techniques. X-ray photoelectron spectroscopy (XPS) and energy dispersive...
We studied effects of metal catalyst and gas composition on the chemical vapor deposition (CVD) growth of horizontally aligned single-walled carbon nanotubes (SWCNTs) on r-plane sapphire substrates. The SWCNTs are sitting on the substrate and aligned along [11¯01¯] direction of the sapphire surface. A combinatorial metal deposition method was applied for single and binary metal catalysts to systematically...
Chemical vapor infiltration was used for the production of carbon/carbon composites based on exfoliated graphite and pyrolytic carbon. Two different exfoliated graphites compacted to densities of 0.05–0.4g/cm 3 were used as a preform. The influence of the synthesis conditions (temperature, pressure, time etc.) on the degree of infiltration, the pyrolytic carbon morphology and the C/C composite...
We present both thermal and electrical conduction properties of vertically aligned carbon nanotubes (VACNTs), synthesized by the water-assisted chemical vapor deposition method using Fe–Ti–O nanoparticles as catalyst. Thermal diffusivity and electrical resistance of VACNTs have been measured by the laser flash method and direct-current four-terminal method, respectively. The VACNTs are found to have...
Graphene oxide platelets synthesized by using a chemical exfoliation method were dispersed in a suspension of ZnO nanoparticles to fabricate ZnO/graphene oxide composite. Formation of graphene oxide platelets (with average thickness of ∼0.8nm) hybridized by ZnO nanoparticles (with average diameter of ∼20nm) was investigated. The 2D band in Raman spectrum confirmed formation of single-layer graphene...
A method of carbon nanotubes (CNTs) oxidation at room temperature using ozone with added water vapor is described. The resulting CNTs were characterized by Fourier transform infrared, X-ray photoelectron spectroscopy, and scanning and transmission electron microscopy. These show that more oxygenated functional groups could be grafted onto the CNT surfaces due to the addition of water vapor, compared...
Hierarchical carbon/carbon–SiC composites have been prepared by a carbothermal reduction process using impregnated silica as a precursor and 3D needle-punched C/C composites as templates at 1450°C. Dense SiC layers surrounding the pyrocarbon were synthesized by further heat-treatments at 1600°C. The resulting composites are composed of turbostratic carbon, β-SiC and 4H type α-SiC, and show pseudo-plastic...
A simple method for extracting otherwise insoluble fullerenes into organic solvents is presented. The fullerenes are reduced to anionic charge states by contact with zinc in the presence of an alkylphosphonium salt in tetrahydrofuran. The anionic fullerenes become soluble, and the non-fullerene carbon matrix is separated by filtration. The anionic fullerenes can then be precipitated from solution...
We fabricated a piezoresistive composite using multi-walled carbon nanotubes (MWCNTs) as a conductive filler and polydimethylsiloxane (PDMS) as a polymer matrix, which operated in the extremely small pressure range required for finger-sensing. To achieve a homogeneous dispersion of MWCNTs in PDMS, the MWCNTs were modified by a polymer wrapping method using poly(3-hexylthiophene) (P3HT). The percolation...
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