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Nitrogen-, phosphorous- and boron-doped carbon nanotubes (N-CNTs, P-CNTs and B-CNTs) were prepared by a chemical vapor deposition method using xylene as carbon source and aniline-NH 3 , triphenyl phosphine and triethyl borate as nitrogen, phosphorous and boron precursors, respectively. By tailoring the composition of reactants and reaction atmosphere, N-CNTs with nitrogen contents from 0%...
Carbon nanotube yarn and sheet were activated using radio frequency, atmospheric pressure, helium and oxygen plasmas. The nanotubes were exposed to the plasma afterglow, which contained 8.0×10 16 cm −3 ground state O atoms, 8.0×10 16 cm −3 metastable O 2 ( 1 Δ g ), and 1.0×10 16 cm −3 ozone. X-ray photoelectron spectroscopy and...
We have clarified the reason that aluminum (Al) buffer layers prepared by sputtering on catalytic substrates are stable for single-walled carbon nanotube forest synthesis on chemical vapor deposition. We have focused on the difference between thermal evaporation and sputtering as the method for the preparation of the buffer layers and have analyzed the Al layers using X-ray photoelectron spectroscopy...
In situ wide-angle X-ray diffraction and small-angle X-ray scattering measurements have been performed during axial compression tests of composite strands of polyacrylonitrile-based carbon fibers with varying carbon layer stacking height and the changes in the crystallite and the microvoid structure have been analyzed. The longitudinal length of microvoids, the orientation parameter of the carbon...
We present the electronic structure of graphite oxide in the vicinity of the Fermi level measured using ultraviolet photoemission and inverse photoemission spectroscopies and compare it with X-ray absorption spectra. The expected p-type behavior of graphite oxide is not observed at the surface and the presence of band bending is invoked. The observed electronic structure of graphite oxide exhibited...
The effect of heat treatment on the strength and toughness of carbon fiber/silicon carbide composites (C/SiC) with different pyrolytic carbon (PyC) interphase thicknesses was investigated. It was found that as the heat treatment temperature (HTT) increases to 1900°C, the strength and toughness of a low strength specimen (LSS, thin PyC ≈40nm) increase by as much as 43.2% and 274.0%, while those of...
C/C–ZrC–SiC composites were prepared by precursor infiltration and pyrolysis process using a mixture solution of organic zirconium-containing polymer and polycarbosilane as precursors. Porous carbon/carbon (C/C) composites with density of 0.92, 1.21 and 1.40g/cm 3 were used as preforms, and the effects of porous C/C density on the densification behavior and ablation resistance of C/C–ZrC–SiC...
Graphene wrapping is used to experimentally understand how a carbon coating works in improving the electrochemical performance of the LiFePO 4 cathode for a lithium ion battery. A full wrapping of LiFePO 4 by graphene is realized by a self-assembly driven by the electrostatic interaction in a graphene oxide suspension. Results indicate that a partial graphene wrapping provides a balance...
A C–SiC composite with a thin layer of carbon surrounding the SiC substrate has been produced by the reaction of SiC with CCl 4 . The pore structures, graphitization levels and the chemical compositions can be finely modulated by the synthesis temperature, and atmosphere. A higher synthesis temperature accelerates the chlorination rate, increases the thickness of carbon layers and enhances...
Photoresist, which is frequently used in existing microelectronics processing, can be pyrolyzed to form a conductive carbon film. We demonstrate that a pyrolysis technique of SPR-220 photoresist, consisting of heating in Ar ambient to 900°C followed by further annealing in an H 2 /Ar mixture, results in a high surface area porous carbon, applicable to supercapacitor electrode fabrication....
We investigated heterojunctions of Si with large-area high-quality monolayer and multi-layer graphene, as well as thin transparent graphite. We show that by controlling the transmittance and sheet resistance of large-area graphitic electrodes, it is possible to obtain solar cells with power conversion efficiency (PCE) exceeding 3% without any doping requirements. Our calculations indicate that such...
In low earth orbit (LEO), components of space systems are exposed to damaging hypothermal atomic oxygen and thermal fatigue. Carbon nanotube (CNT) wires are candidate materials for different applications in space systems. Thirty-yarn CNT wire’s behavior was evaluated when exposed to hypothermal atomic oxygen and thermal fatigue. CNT wire specimens were exposed to a nominal fluence of hypothermal atomic...
Sodium ion battery is a promising electrical energy storage system for sustainable energy storage applications due to the abundance of sodium resources and their low cost. In this communication, the electrochemical properties of sodium ion storage in reduced graphene oxide (RGO) were studied in an electrolyte consisting of 1M NaClO 4 in propylene carbonate (PC). The experimental results show...
The effect of titanium (Ti) added to the top layer of an aluminum (Al)/iron (Fe)/Al (bottom) sandwich catalytic substrate was studied. The Ti caused a significant lengthening in the single-wall carbon nanotube forest produced by chemical vapor deposition (CVD). In general, particles of iron oxide on the Al/Fe/Al catalytic substrate are formed by exposure to the atmosphere during deposition process...
We examined the potential of a series of aromatic moieties with different electron-donating ability to alter SWCNT electronic properties. The selected aromatic moieties included p-amino-phenylalanine, 3-[4-(dimethylamino)phenyl]propanoic acid, tyrosine, tryptophan, and 4-pyridylalanine. These moieties contained exocyclic electron-donor substituents, such as amine, dimethylamine, and hydroxyl groups,...
We report a method of improving the alignment of carbon nanotubes (CNTs) in a solid strand prepared from a CNT forest without dispersing and regrouping them. The use of a lubricant loosens the interconnections between the carbon nanotubes so that they can slide relative to each other and align themselves longitudinally. A highly stretchable polymer gel fibre is used as a carrier to apply the lubricant...
Hydrothermal carbonization followed by chemical activation is utilized to convert paper pulp mill sludge biowaste into high surface area (up to 2980m 2 g −1 ) carbons. This synthesis process employs an otherwise unusable byproduct of paper manufacturing that is generated in thousands of tons per year. The textural properties of the carbons are tunable by the activation process, yielding...
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