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We demonstrate that domain structure of single-layer graphene grown by ambient pressure chemical vapor deposition is strongly dependent on the crystallinity of the Cu catalyst. Low energy electron microscopy analysis reveals that graphene grown using a Cu foil gives small and mis-oriented graphene domains with a number of domain boundaries. On the other hand, no apparent domain boundaries are observed...
Novel magnetic resonance imaging (MRI) contrast agents composed of multiwalled carbon nanotubes decorated with magnetic iron oxide nanoparticles were explored. They were functionalized with multilayer polyelectrolytes through layer-by-layer assembling and were shown to be hydrophilic, biocompatible, and have a high MRI contrast. A targeted ligand folic acid was chemically bonded to the functionalized...
Cobalt core/graphite shell nanostructures anchored on graphene sheets have been prepared by a chemical vapor deposition process. Transmission electron microscope images show that the cobalt nanoparticles (10–30nm) are encapsulated by a graphitic shell with a thickness of ∼3nm. Magnetic measurements reveal that the material has a typical ferromagnetic behavior with a saturation magnetization of 71...
Interfacial fracture between an individual fiber and the pyrocarbon matrix in carbon/carbon composites has been studied in a 300kV high-resolution transmission electron microscope (TEM) by using an integrated TEM-atomic force microscope piezodriven holder. Force vs. displacement curves were acquired by bending a part of a carbon fiber perpendicular to the transverse section of the fiber. The process...
We report the very rapid growth of carbon nanotubes (CNTs) at high temperatures that can be tolerated by glass substrates. Glass substrates with metal microelectrodes and sputtered catalysts are heated by a pulsed current in a chemical vapour deposition gas environment for 0.5–1s to synthesize CNTs of several micrometres in height without damaging the glass substrate. CNTs with structures from single-walled...
A method is presented to tailor the lateral size of graphene oxide (GO) in the range of 10–100nm and simultaneously tailor its edge structure by oxidation with periodic acid in a one-pot process. The obtained GO nanosheets are photoluminescent and exhibit lateral size-dependent behavior. The emission wavelength could be tuned from 550 to 470nm by decreasing the lateral size. The fluorescence of GO...
The oxidation kinetics at ambient temperature of an ex-cellulose activated carbon cloth has been investigated using an aqueous solution of NaOCl. Oxidized samples were weighed and characterized by TG–TPD–MS and XPS. Weight analysis revealed three stages during the course of oxidation. The first is dominated by the creation of oxygen groups at the carbon surface with an initial oxygen uptake rate assessed...
We employed a novel three-step reduction of graphite oxide (GO) to obtain graphene nanosheets with high specific surface area and good dispersion in aqueous solution. Iron powder, as a mild and environmentally friendly reducing agent, was used at first in partial-reduction of GO and then, sulphonic functional groups (–SO3−) were introduced on the surface of partially reduced GO. The negatively charged...
Copper nanoparticles encapsulated by multi-layer graphene have been produced in large quantity (in grams) by metal-organic chemical vapor deposition at 600°C with copper(II) acetylacetonate powders as precursor. The obtained graphene/copper shell/core nanoparticles were found to be formed by a novel coalescence mechanism that is quite different from the well-known dissolution–precipitation mechanism...
A simple one-step method of the synthesis of carbon nanotubes (CNTs) grafted onto carbon fibers (CFs) was developed using catalysts formed in an ethanol flame, where the reducing atmosphere prevents the CFs from combustion and reduces the catalyst precursor to catalyst particles on the fibers. The growth process was studied and both the type and concentration of catalyst ions were found to affect...
Composite films consisting of polypyrrole (PPy) and graphene oxide (GO) were electrochemically synthesized by electrooxidation of 0.1M pyrrole in aqueous solution containing appropriate amounts of GO. Simultaneous chronoamperometric growth profiles and frequency changes on a quartz crystal microbalance showed that the anionic GO was incorporated in the growing GO/PPy composite to maintain its electrical...
A stable, extensive amine functionalization was introduced on the surface of an activated carbon (AC) through very effective grafting of a polyethyleneimine layer onto the AC surface. The procedures used are simple, sustainable and easily scalable. Among the large variety of possible applications that the polyamine functionality confers to the AC, its outstanding properties as Pd(II) adsorbent are...
We have observed the nucleation and growth of carbon nanowalls at the electrode surface during laser ablation experiments conducted in water under the presence of an electric field. The nanowalls consist graphene sheets (2–6 layers) in a flower-like arrangement which uniformly cover the whole electrode surface. The deposition mechanism and the role of the plasma-produced carbon species are discussed.
We have developed an easy and scalable chemical reduction method assisted by microwave irradiation for the synthesis of reduced graphene oxide (RGO) nanosheets in solid state. The as-synthesized RGO is characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetry, X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy. It is revealed that the...
Core/shell materials with a movable Fe 3 O 4 core and a carbon shell were prepared using polypyrrole as carbon precursor. They are good candidates as metal catalyst supports due to their magnetic property and large surface area. The outer carbon shell thickness could be well-controlled. In addition, the Fe 3 O 4 @C materials displayed good resistance to acids, which...
Reduced graphene oxide (RGO) with a layered and porous structure was synthesized by thermal exfoliation of graphite oxide. Synthesized RGO is very light weight and flaky. The formation of RGO was studied using Fourier transform infrared and Raman spectroscopies, X-ray diffraction and scanning electron microscopy. Composites were prepared by dispersing 2%, 4% and 10% by weight of the synthesized RGO...
Dense and homogeneous multi-walled carbon nanotube/metal composites are prepared by powder metallurgy. The distribution of the nano-reinforcements in the matrix is studied by scanning electron microscopy and Raman spectroscopy. The mechanical properties of the composites are determined by means of static tensile tests and Vickers micro-hardness measurements. We show that a homogeneous dispersion of...
We have observed that during temperature-dependent four-terminal resistance measurement of monolayer graphene, the resistance exhibits anomalous rising and falling behavior at different temperature regions. At lower temperature region (2–200K) the resistance decreases gradually, but when the temperature rise further it turn to a sudden increase, and after 280K it resumes gradual decrease. The rising...
Fluorine functionalization, using XeF 2 , was investigated as a way to enhance atomic layer deposition (ALD) of thin, high-κ dielectrics on epitaxial graphene, which would enable the realization of graphene-based device technologies. The XeF 2 dosage time was correlated with oxide coverage and morphology as well as its overall effect on the underlying graphene properties. An optimum...
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