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Carbon nanotubes (CNTs) are regarded as promising transistor building blocks for the future integrated circuits. For real circuits applications, high I on /I off ratio with low I off are desired for the transistor due to the requirements of high working speed and low power consumption. However, due to the intrinsic ambipolarity of the CNT, pronounced ambipolar behaviors with considerably high I...
The lithium-sulfur (Li-S) batteries are potential candidates for next-generation power sources with very high-energy-density. The rational integration of three dimensional (3D) carbon skeletons into sulfur cathode is an efficient and effective route to full use of conductive scaffolds with chemical and mechanical stability and ability to accommodate large amount of active materials. Herein, a 3D free-standing...
The efficient fabrication of carbon nanotube (CNT) bundles is the prerequisite for their bulk applications. However, the poor fluidization behavior of metal nanoparticle catalysts hinders the effective growth of high quality CNT bundles. Herein magnetically assisted fluidized bed (MFB) chemical vapor deposition was proposed for bulk growth of long CNT arrays. By introducing a uniform magnetic field...
The graphene/carbon nanotube (CNT) hybrids are considered as one of the most advanced nanostructures with intrinsically self-dispersion properties for large-volume applications. However, owing to the limited understanding on the complex growth mechanism and non-linear kinetics, rational design of growth procedures and related multiphase reactors for the production of the hybrids remain great challenges...
Lithium-ion batteries (LIBs) are extensively used in numerous portable devices such as smart-phones and laptops. However, current LIBs based on the conventional intercalation mechanism cannot meet the requirements of the electronics industry and electric vehicles although they are approaching their theoretical capacity. Therefore, it is extremely urgent to seek for systems with higher energy densities...
The rational integration of conductive nanocarbon scaffolds and insulative sulfur is an efficient method to build composite cathodes for high-energy-density lithium–sulfur batteries. The full demonstration of the high-energy-density electrodes is a key issue towards full utilization of sulfur in a lithium–sulfur cell. Herein, carbon nanotubes (CNTs) that possess robust mechanical properties, excellent...
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...
Herringbone carbon nanofibers (CNFs) were efficiently produced by chemical vapor deposition on Ni nanoparticles derived from layered double hydroxide (LDH) precursors. The as-obtained CNFs with a diameter ranging from 40 to 60nm demonstrated herringbone morphologies when they grew on Ni/Al LDH derived catalysts both in the fixed-bed and fluidized-bed reactor. The Ni/Mg/Al, Ni/Cu/Al, as well as Ni/Mo/Mg/Al...
High efficient sulfur cathode materials were constructed by the incorporation of aligned sulfur-coated carbon nanotubes (CNTs) and a polyethylene glycol (PEG) barrier at one end. During the charge and discharge of lithium sulfur batteries, high Li ion storage performance can be achieved on the composite electrode, which was benefited from both the aligned CNT structure and the polymer barrier. Aligned...
CoMgAl layered double hydroxides were prepared as catalysts for the in situ synchronous growth of graphene and single-walled carbon nanotubes (SWCNTs) from methane by chemical vapor deposition. The as-calcined CoMgAl layered double oxide (LDO) flakes served as the template for the deposition of graphene, and Co nanoparticles (NPs) embedded on the LDOs catalyzed the growth of SWCNTs. After the removal...
Self-organization of nitrogen-doped carbon nanotube (N-CNT) double helices was achieved by chemical vapor deposition (CVD) with Fe–Mg–Al layered double hydroxides (LDHs) as the catalyst precursor. The as-obtained N-CNT double helix exhibited a closely packed nanostructure with a catalyst flake on the tip, which connected the two CNT strands on both sides of the flake. A mechanism for the self-organization...
A free-standing graphene oxide film (GOF) obtained by self-assembly at a liquid/air interface was annealed in a confined space between two stacked substrates to form a free-standing highly conductive graphene film. Characterization indicates that the oxygen-containing functional groups (e.g. epoxy, carboxyl, and carbonyl) were removed as small molecules (e.g. H 2 O, CO 2 , and CO)...
Single-walled carbon nanotube (SWCNT) double helices were fabricated with directly synthesized FeMoMgAl layered double hydroxide flakes as the catalyst precursor. The as-obtained SWCNT double helices were closely packed, while the screw pitches of the double helices were tunable from 2 to 10μm. Straight millimeter-length SWCNT yarns can be obtained by further stretching the SWCNT double helices.
A simple method is reported for the fast growth of millimeter-tall aligned carbon nanotubes (CNTs). Two silicon substrates were stacked with catalyst layers face to face and CNT growth occurred between them. Based on in situ monitoring, the growth rate of aligned CNTs in stacked area was found to be much (over one magnitude) higher than that in the area with a single substrate. The phenomenon was...
Natural sepiolite mineral was used as a catalyst and catalyst support for the efficient growth of single-walled carbon nanotubes (SWCNTs). With the introduction of hydrogen, uniform active metal nanoparticles can be formed in the fibrous structure of sepiolite ore. High-quality SWCNTs with few defects and a large aspect ratio (over 10 4 ) were synthesized. The structure of the CNTs was modified...
The buckling and fracture modes of thick (diameter >20nm) multiwall carbon nanotubes (MWCNTs) under compressive stress were examined using in situ transmission electron microscopy. The overall dynamic deformation processes of the MWCNTs as well as the force/distance curves can be obtained. The buckling behavior of MWCNTs under compression falls into two categories, the first is non-axial buckling...
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...
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...
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