Synergetic carbon nanotube growth

Parker, Jason; Wong, H.-S. Philip

doi:10.1016/j.carbon.2013.05.053

Cited by 6 publications

(6 citation statements)

References 34 publications

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“…It is believed that, the CNT growth will terminate when the number density at the bottom reaches the threshold, implying that some CNTs that stop growing can be carried upward by the growing CNTs due to mechanical interaction, which undoubtedly shapes the microstructure of the VACNTs. Besides, it was found that, small catalysts which were close to large ones showed an enhanced growth rate of CNTs than the catalysts which had similar small sizes but were separately distributed from each other 30 . It was believed that, this “synergetic growth” effect was probably caused by some intermediate active substance, the generation of which was greatly related to catalysts.…”

Section: Growth Kinetics Of Vacntsmentioning

confidence: 97%

Growth mechanism and kinetics of vertically aligned carbon nanotube arrays

Liu

Shi

Jiang

et al. 2021

EcoMat

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Carbon nanotubes (CNTs) exhibit excellent mechanical, electrical, thermal, and chemical properties and show promising application potentials in numerous fields. Among different types of CNTs, vertically aligned CNT arrays (VACNTs) exhibit more superiors due to their good alignment, controllable structures and morphologies, and easy mass‐production, and so forth. During the past years, extensive efforts were put into the controlled synthesis of VACNTs with desired structures and morphologies. Among these efforts, it should be noted that, it is of significant importance to improve the array lengths of VACNTs, especially for the fabrication of VACNTs‐based fibers, transparent flexible films, and other functional materials, and so forth. However, it still remains a big challenge to synthesize VACNTs with length over centimeters. In this review, we summarize the growth mechanism, kinetics, growth factors of VACNTs, and the strategies for how to improve their array lengths. Finally, we also propose our outlook on the future development of VACNTs.

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Section: Growth Kinetics Of Vacntsmentioning

confidence: 97%

Growth mechanism and kinetics of vertically aligned carbon nanotube arrays

Liu

Shi

Jiang

et al. 2021

EcoMat

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“…8,10−12 The long-held understanding of CNT formation is that it occurs through the vapor−liquid−sold (VLS) and vapor− solid−solid (VSS) models. 13 VLS and VSS postulate that vapor-phase hydrocarbons thermally decompose and diffuse through a liquid or solid catalyst nanoparticle, and then precipitate on the surface as solid CNT. 14 Originally developed for solid Si whiskers 15 and then applied to carbonaceous materials, 16−19 these precipitation-based mechanisms have good experimental support but lack chemical detail and provide few "levers" with which to manipulate CNT structure.…”

mentioning

confidence: 99%

Modifying the Molecular Structure of Carbon Nanotubes through Gas-Phase Reactants

et al. 2023

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Current approaches to carbon nanotube (CNT) synthesis are limited in their ability to control the placement of atoms on the surface of nanotubes. Some of this limitation stems from a lack of understanding of the chemical bond-building mechanisms at play in CNT growth. Here, we provide experimental evidence that supports an alkyne polymerization pathway in which short-chained alkynes directly incorporate into the CNT lattice during growth, partially retaining their side groups and influencing CNT morphology. Using acetylene, methyl acetylene, and vinyl acetylene as feedstock gases, unique morphological differences were observed. Interwall spacing, a highly conserved value in natural graphitic materials, varied to accommodate side groups, increasing systematically from acetylene to methyl acetylene to vinyl acetylene. Furthermore, attenuated total reflectance Fourier-transfer infrared spectroscopy (ATR-FTIR) illustrated the existence of intact methyl groups in the multiwalled CNTs derived from methyl acetylene. Finally, the nanoscale alignment of the CNTs grown in vertically aligned forests differed systematically. Methyl acetylene induced the most tortuous growth while CNTs from acetylene and vinyl-acetylene were more aligned, presumably due to the presence of polymerizable unsaturated bonds in the structure. These results demonstrate that feedstock hydrocarbons can alter the atomic-scale structure of CNTs, which in turn can affect properties on larger scales. This information could be leveraged to create more chemically and structurally complex CNT structures, enable more sustainable chemical pathways by avoiding the need for solvents and postreaction modifications, and potentially unlock experimental routes to a host of higher-order carbonaceous nanomaterials.

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“…Recently, Parker et al . showed that placement of thin catalyst micropatterns adjacent to larger patterns influenced the smaller patterns and caused them to produce horizontally oriented CNT structures that bent away from the larger patterns . Earlier, Borgstrom et al .…”

mentioning

confidence: 99%

“…Recently, Parker et al showed that placement of thin catalyst micropatterns adjacent to larger patterns influenced the smaller patterns and caused them to produce horizontally oriented CNT structures that bent away from the larger patterns. 13 Earlier, Borgstrom et al demonstrated synergetic effects in gallium phosphide (GaP) nanowire growth, owing to both gas-phase and surface diffusion interactions influenced by the proximity and diameter of individual nanowires. 14 For CNT growth by CVD, Bronikowski suggested that growth-promoting byproducts are generated during decomposition of the feedstock gas in areas of high catalyst concentration.…”

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confidence: 99%

Synergetic Chemical Coupling Controls the Uniformity of Carbon Nanotube Microstructure Growth

2014

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Control of the uniformity of vertically aligned carbon nanotube structures (CNT "forests"), in terms of both geometry and nanoscale morphology (density, diameter, and alignment), is crucial for applications. Many studies report complex and sometimes unexplained spatial variations of the height of macroscopic CNT forests, as well as variations among micropillars grown from lithographically patterned catalyst arrays. We present a model for chemically coupled CNT growth, which describes the origins of synergetic growth effects among CNT micropillars in proximity. Via this model, we propose that growth of CNTs is locally enhanced by active species that are catalytically produced at the substrate-bound nanoparticles. The local concentration of these active species modulates the growth rate of CNTs, in a spatially dependent manner driven by diffusion and local generation/consumption at the catalyst sites. Through experiments and numerical simulations, we study how the uniformity of CNT micropillars can be influenced by their size and spacing within arrays and predict the widely observed abrupt transition between tangled and vertical CNT growth by assigning a threshold concentration of active species. This mathematical framework enables predictive modeling of spatially dependent CNT growth, as well as design of catalyst patterns to achieve engineered uniformity.

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Synergetic carbon nanotube growth

Cited by 6 publications

References 34 publications

Growth mechanism and kinetics of vertically aligned carbon nanotube arrays

Growth mechanism and kinetics of vertically aligned carbon nanotube arrays

Modifying the Molecular Structure of Carbon Nanotubes through Gas-Phase Reactants

Synergetic Chemical Coupling Controls the Uniformity of Carbon Nanotube Microstructure Growth

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