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X-ray ptychographic tomography has been recently developed for quantitative imaging of specimens on the nanometer scale. Here we present its application for the characterization of carbon fibers by mapping in three dimensions the mass density of entire fibers with diameters of several tens of micrometers with a resolution of about 100nm. We characterized two fibers produced from two different precursors,...
The corrosion behaviour of four carbon materials namely low density graphite, high density graphite, glassy carbon and pyrolytic graphite were investigated in molten LiCl–KCl electrolyte medium at 600°C for 2000h under high pure argon atmosphere. Structural and microstructural changes in the carbon materials after exposure to molten chloride salt were investigated from the weight change and using...
Large size and high quality graphene grown by chemical vapour deposition (CVD) has been fabricated into an array of discrete graphene sheets with well-defined sizes and shapes. A fabrication process based on nanoimprint lithography has been developed to achieve shape tunability with sizes ranging from micrometer to nanometer. The technique preserves the quality of the CVD grown graphene and offers...
In this work, we have studied morphological, structural and phase changes in amorphous carbon-encapsulated silver nanoparticles (Ag@C) upon treatment by H 2 S gas. The carbon shells have been found to present no impassable obstacles for the silver sulfide to form. The growth of Ag 2 S nanocrystals occurs on the outer surface of the carbon shell, the size of the encapsulated silver...
A new and simple method, using water as a potential molecular probe, is proposed for the determination of the concentration of surface oxygen groups on carbon adsorbents. The procedure is based on a determination of the Henry constant between a water molecule and a functional group from the volume integration of the Boltzmann factor over the accessible space around the functional group. Three porous...
Graphene oxide (GO) was firstly employed as nanoscale reinforcement fillers in hydroxyapatite (HA) coatings by a cathodic electrophoretic deposition process, and GO/HA coatings were fabricated on pure Ti substrate. The transmission electron microscopy observation and particle size analysis of the suspensions indicated that HA nanoparticles were uniformly decorated on GO sheets, forming a large GO/HA...
Junctions are the key component for 3D CNT-graphene seamless hybrid nanostructures attractive for numerous innovative applications. Growth mechanism of junctions of vertical carbon nanotubes (CNTs) growing from graphene in the presence of iron nanoparticles as catalysts was simulated using quantum mechanical molecular dynamics methods. When nanotube grew on graphene via a “base-growth” mechanism,...
This paper describes a novel technique for determining the residual life of activated carbon material through changes in response when placed inside a resonant cylindrical cavity excited at microwave frequencies. The technique has been validated through the co-ageing of two activated carbon batches at 40°C and 80% relative humidity over a period of 7months. Two regions in the microwave spectra, 7500...
Surface roughness, porosity and contact angles of different carbon paper materials (TORAY paper with PTFE from 0% to 60% of and SGL paper with 0% and 20% of PTFE) suitable as electrodes in microbial fuel cells were investigated. The changes of contact angle between dry and clean anode surfaces and the ones after exposure to wastewater were measured using different liquids (pure water and sodium acetate...
Solutions of alkali metal salts of single-walled carbon nanotubes (SWNTs) show individualization of the nanotubes without sonication-induced shortening. Bundles are fully exfoliated and length measurements show mean length over one micron, a rare case for liquid formulation of SWNTs. These concentrated solutions of individualized nanotubes in organic solvents can be freeze dried leading to ultralight,...
We demonstrate the direct growth of carbon nanotube (CNT) forests on metallic titanium (Ti) coatings by single-step chemical vapor deposition. This was achieved by catalyst engineering, which involves a novel design of Fe/Ti/Fe nanostructure sputtering coated on SiO 2 /Si wafers. The Fe sublayer, an additional catalyst added to the conventional catalyst/support design, plays a key role in...
Charge transport properties of TiO 2 –multiwalled carbon nanotube (MWCNT) composites were investigated. The TiO 2 –MWCNT composites were fabricated by spark plasma sintering of a mixture of TiO 2 nanoparticles and MWCNTs. Temperature-dependent electrical conductivities of the composites reveal that the percolation threshold for the MWCNT network is affected by temperature,...
This paper presents a thermogravimetric analysis of catalytic methane decomposition using ordered mesoporous carbon nanorods (CMK-3) and ordered mesoporous carbide-derived carbon (DUT-19) as catalysts. X-ray diffraction and N 2 physisorption analyses were performed for both fresh catalysts. Threshold temperatures for methane decomposition with DUT-19 and CMK-3 were estimated by three different...
Catalyst-free and self-assembled growth of graphene flakes (GFs) on carbon nanotube (CNT) arrays have been realized by using microwave plasma enhanced chemical vapor deposition. The shape of GFs was highly manipulated by adjusting the growth time, C concentration, and microwave power. We qualitatively discussed the nucleation and growth mechanism of GFs based on the growth parameter–GF shape studies...
A family of layered double hydroxides (LDHs) with varied Fe contents were employed as catalyst precursors for the controllable bulk growth of few-layer graphene/single-walled carbon nanotube (G/SWCNT) hybrids in a fluidized-bed reactor through chemical vapor deposition of methane at 950°C. All the G/SWCNT hybrids exhibited the morphology of SWCNTs interlinked with graphene layers. The purity, thermal...
An asymmetric aqueous capacitor was constructed by employing zeolite-templated carbon (ZTC) as a pseudocapacitive positive electrode and KOH-activated carbon as a stable negative electrode. The asymmetric capacitor can be operated with the working voltage of 1.4V, and exhibits an energy density that is comparable to those of conventional capacitors utilizing organic electrolytes, thanks to the large...
Graphite electrodes were electrochemically cycled in Li-ion cells at 50 and 60°C in order to determine the changes in their surface properties in comparison to the electrodes tested at 25°C. A 17% drop in planar capacity occurred during the first cycle at 60°C compared to a 40% at 25°C and reduced the amount of damage that occurred to graphite due to a rapidly formed solid electrolyte interphase (SEI)...
Glucose oxidase biosensors were fabricated by vacuum-impregnation of a glucose oxidase in a polyvinyl alcohol (PVA) aqueous solution into carbon nanotube non-woven fabrics (CNTFs). The performance of the biosensor was evaluated by an electrochemical method, using the biosensors as working electrode, Pt wire as a counter electrode and Ag/AgCl as a reference electrode. The electrical conductivity of...
The erosion of a four-direction carbon/carbon composite test piece using a low-velocity, high-particle-concentration two-phase jet was studied by the hot firing test of a small solid rocket motor with an elaborately designed flow path. The linear ablation rates were measured. The ablation surface and microstructure of the carbon/carbon composites were studied by scanning electron microscopy, and the...
Carbon dots (CD) are luminescent nanomaterial with unique properties that show great potential in many applications. Herein, branched polyethyleneimine-based carbon dots (PCD) are prepared from branched polyethyleneimine by oxidation and a modified hydrothermal reaction. Structure and composition analysis indicate that obtained PCD possesses a 3–4nm in diameter and a graphitic structure with lattice...
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