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The preparation of effective dispersions of carbon nanotubes (CNTs) presents a major impediment to the extension and utilization of CNTs. CNTs intrinsically tend to bundle and/or aggregate. The prevention of such behavior has been explored by testing various surface modification techniques to improve the dispersibility of CNTs in a variety of solvents and polymer matrices. General guidelines for the...
Pt and Pd–Pt nanoparticles were anchored on reduced graphene oxide (RGO) with the aid of poly(diallyldimethylammonium chloride) (PDDA), where Pt and Pd ions were first attached to PDDA-functionalized graphene oxide sheets and the encased metal ions and graphene oxide were then reduced simultaneously by ethylene glycol. As supported by transmission electron microscopy, metal nanoparticles, of small...
Small angle X-ray scattering and molecular dynamics simulation were used to study the microvoid evolution in carbon fibers (CFs) during tensile deformation. The stress–strain relation and the parameters of microvoids, such as the length, diameter, orientation angle and relative volume were measured. The results demonstrated that during the tensile deformation of CFs, (1) the microvoid volume increased...
A mesoporous carbon nanofiber-modified pyrolytic graphite electrode (MCNF/PGE) has been prepared and applied to the simultaneous electrochemical determination of dopamine (DA), uric acid (UA) and ascorbic acid (AA). The oxidation overpotentials of these biomolecules decrease significantly, the overlapping of these peaks in bare PGE is well resolved, and their anodic peak currents increase dramatically...
Carbon nanofibers with a polygonal cross section were synthesized using catalytic chemical vapor deposition over Fe–Sn, Ni–Sn or Co–Sn catalysts. Their morphologies were characterized by scanning and transmission electron microscopy. Edges connecting of two walls can be clearly observed and some adjacent walls have a V-shape. The lengths of the sides of the polygonal cross sections range from 150...
Doping effects on exfoliated graphenes induced by methyl orange (MO) have been studied by spatially resolved Raman spectroscopy. When the MO molecules were adsorbed on the top of graphenes, the charge transfer between them caused two outcomes simultaneously. One is the strong chemical doping in graphenes and the other is the enhanced Raman signals of MO molecules. Our finding provides a potential...
We prepared and characterized multi-walled carbon nanotube (MWCNT) solids by de-fluorination of fluorinated MWCNTs using spark plasma sintering. In order to investigate the influence of the structure of MWCNT on the mechanical strength of the resulting solids, MWCNTs used in this experiment were as-defected MWCNTs modified by nitric acid and as-purified ones as non-defected nanotubes by comparison...
Electrically conductive multi-walled nanotube (MWCNT)/poly(vinylidene fluoride) (PVDF) composites with a segregated structure were prepared by high-speed mechanical mixing method. It was found that MWCNTs were uniformly dispersed on polymer particle surfaces. At the MWCNTs composition of 0.1vol.%, the composites exhibited a dramatic enhancement in electrical conductivity by 11 orders of magnitude...
Multiwalled carbon nanotubes have been produced by ethylene catalytic chemical vapor deposition and used to fabricate thick and dense freestanding films (“buckypapers”) by membrane filtering. Field emission properties of buckypapers have been locally studied by means of high vacuum atomic force microscopy with a standard metallic cantilever used as anode to collect electrons emitted from the sample...
We report the atmospheric pressure chemical vapor deposition (CVD) growth of single-layer graphene over a crystalline Cu(111) film heteroepitaxially deposited on c-plane sapphire. Orientation-controlled, epitaxial single-layer graphene is achieved over the Cu(111) film on sapphire, while a polycrystalline Cu film deposited on a Si wafer gives non-uniform graphene with multi-layer flakes. Moreover,...
We present a comprehensive study of the parameter space for single layer graphene growth by chemical vapor deposition on Cu. The temperature is the most widely recognized control parameter in single layer graphene growth. We show that the methane-to-hydrogen ratio and the growth pressure also are critical parameters that affect the structural perfection and the cleanliness of graphene. The optimal...
Vapour grown carbon nanofibre (VGCNF)/rubbery epoxy (RE) composites were produced, by either mechanical mixing, three-roll milling (RM) or combined ultrasonication/mechanical mixing. Incorporation of VGCNFs resulted in significant enhancements in the thermal and electrical conductivities of the material. Appropriate selection of processing technique and parameters can help to maximise the potential...
Semiconducting graphene oxide/polyaniline (GO/PANI) composite particles for potential electrorheological (ER) fluid applications were synthesized by the in situ dispersion polymerization of aniline in the presence of GO particles, which were prepared using a modified Hummers method. The electroresponsive ER characteristics of the composite when dispersed in silicone oil exhibited a phase transition...
The electrical resistivity of CNT yarns of diameters 10–34μm, spun from multi-walled carbon nanotube arrays, have been determined from 2 to 300K in magnetic fields up to 9T. The magnetoresistance is large and negative at low temperatures. The thermal conductivity also has been determined, by parallel thermal conductance, from 5 to 300K. The room-temperature thermal conductivity of the 10μm yarn is...
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