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By acetylene decomposition at 450°C over the Fe–Cu nanoparticles (Fe:Cu molar ratio=29:1, 5:1) derived from a combined sol–gel/reduction method, carbon nanobelts (CNBs) and carbon/Fe–Cu hybrid nanoparticles (CNPs) were synthesized simultaneously with high yield. The two carbon species could be easily separated according to color and were collected at different locations of the ceramic plates where...
A molecularly imprinted polymer–graphene oxide (MIP–GO) hybrid material was synthesized by reversible addition and fragmentation chain transfer (RAFT) polymerization using RAFT agent functionalized GO as chain transfer agent. The formation of this hybrid material was verified by Raman spectroscopy, Fourier transform infrared spectroscopy, and thermal gravimetric analysis. Atomic force microscopy showed...
A family of layered double hydroxides (LDHs), such as Fe/Mg/Al, Co/Mg/Al, and Ni/Mg/Al LDHs, were used as catalysts for the efficient growth of single-walled carbon nanotubes (SWCNTs) in a fluidized bed reactor. The LDH flakes were agglomerated into clusters with sizes ranging from 50 to 200μm, and they can be easily fluidized with a gas velocity ranging from 2.3 to 24cm/s. After calcination and reduction,...
Carbon nanotube (CNT) yarn was drawn directly from super aligned CNT arrays synthesized by an improved floating catalyst chemical vapor deposition method. The synthesis of aligned CNT was performed as a multi-step interim reactant supply reaction to produce a double-layered CNT array in a horizontal quartz tube reactor. During the growth period, most impurities were blocked on the top surface of the...
Using in situ transmission electron microscopy, we observed the nucleation and growth of graphene bilayer edges (BLE) with “fractional nanotube”-like structure from the reaction of graphene monolayer edges (MLEs). Most BLEs showed atomically sharp zigzag or armchair crystallographic facets in contrast to the atomically rough MLEs with irregular shapes, suggesting that the BLEs are much more stable...
Carbon functionalized with sulfonic acid groups has been synthesized using the one-step hydrothermal carbonization of furaldehyde and hydroxyethylsulfonic acid aqueous solution at 180°C for 4h. The carbon exhibited high acidity and comparable activities to sulfuric acid for the traditional acid-catalyzed reactions, which indicated that it has great potential for environment-friendly processes. The...
A parametric study investigating the impacts of loading amount of active phase, growth temperature, H 2 reduction, space velocity, and apparent gas velocity on the intercalated growth of vertically aligned carbon nanotube (CNT) arrays among lamellar catalyst was performed. A series of Fe/Mo/vermiculite catalysts with Fe/vermiculite ratio of 0.0075–0.300 were tested. Metal particles were dispersed...
Free standing vertically-aligned carbon nanotube (CNT) arrays were released from a quartz substrate on a large scale by using CO 2 as an oxidative reagent to weaken the array–substrate interaction and facilitate their harvest. During the oxidation process, amorphous carbon and carbon in contact with metallic particles were preferentially etched, leading to the easy release of high quality...
Fourier transform infrared spectroscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy were applied in this study to demonstrate that multi-walled carbon nanotubes synthesized from ethanol flames (F-MWCNTs) inherently have functional groups on their surfaces. This finding clearly indicates that the covalent functionalization of carbon nanotubes can be achieved...
A carbon/carbon (C/C) composite with a thermal conductivity greater than 500W/mK was used as a heat-redistribution material in a new thermal protection system. Using this material, the temperature at the hot head of a model hypersonic aircraft re-entry cone was sharply decreased, which effectively reduced the thermal burden and protected the hot side from being destroyed.
High purity (99.21wt.%) helical carbon nanotubes (HCNTs) were synthesized in large quantity over Fe nanoparticles (fabricated using a coprecipitation/hydrogen reduction method) by acetylene decomposition at 450°C. Field-emission and transmission electron microscope images reveal that the selectivity to HCNTs (with two or three coiled nanotubes connected to a catalyst nanoparticle) is up to ca. 93%...
Ketjen Black (KB) as an electrocatalyst support was treated at 900°C in the presence of cobalt and nickel nitrates, and characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and nitrogen adsorption measurement. The treated KB (T-KB) exhibits better graphitization and a larger mesopore volume than the untreated material. A Pt electrocatalyst supported...
Large amount of vertically aligned carbon nanotube (CNT) arrays were grown among the layers of vermiculite in a fluidized bed reactor. The vermiculite, which was 100–300μm in diameter and merely 50–100μm thick, served as catalyst carrier. The Fe/Mo active phase was randomly distributed among the layers of vermiculite. The catalyst shows good fluidization characteristics, and can easily be fluidized...
Fluffy carbon nanotubes (CNTs), which are cotton-like macroscopic structures, are obtained by simple high-speed shearing of vertically aligned CNT (VACNT) arrays. The fluffy CNTs are composed of CNT bundles with a diameter of several micrometers, and have an extremely low apparent density of 3–10g/L. A requisite for their formation is the alignment of CNTs in the initial array. The shear between the...
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