The effect of a convection vortex on sock formation in the floating catalyst method for carbon nanotube synthesis

Hou, Guangfeng; Su, Ruitao; Wang, An‐Li; Ng, Vianessa; Liu, Weifeng; Song, Yi; Zhang, Lu; Sundaram, Murali M.; Shanov, Vesselin; Mast, David; Lashmore, D. S.; Schulz, Mark J.; Liu, Yijun

doi:10.1016/j.carbon.2016.02.087

Cited by 57 publications

(34 citation statements)

References 29 publications

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“…As only feeding rate and carrier gas were altered in this case, we consider that it is the decrease of volume of carrier gas that accounts for the reduction of number of CNT loops. Theoretical studies have proposed the existence of back flow at the outlet of a quartz tube inside a high-temperature furnace [ 19 , 20 ]. The back flow boosted by the phenomenon of thermophoresis can trigger local convection vortex which might be more obvious when using a high flow rate, bringing about many CNT loops.…”

Section: Resultsmentioning

confidence: 99%

High-performance single-walled carbon nanotube transparent conducting film fabricated by using low feeding rate of ethanol solution

Ding¹,

Zhang²,

Wei³

et al. 2018

R. Soc. open sci.

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We report floating catalyst chemical vapour deposition synthesis of single-walled carbon nanotubes (SWCNTs) for high-performance transparent conducting films (TCFs) using low feeding rate of precursor solution. Herein, ethanol acts as carbon source, ferrocene and thiophene as catalyst precursor and growth promoter, respectively. By adopting a low feeding rate of 4 µl min−1, the fabricated TCFs present one of the lowest sheet resistances of ca 78 Ω sq.−1. at 90% transmittance. Optical characterizations demonstrate that the mean diameter of high-quality SWCNTs is up to 2 nm. Additionally, electron microcopy observations provide evidence that the mean length of SWCNT bundles is as long as 28.4 µm while the mean bundle diameter is only 5.3 nm. Moreover, very few CNT loops can be found in the film. Remarkably, the fraction of individual SWCNTs reaches 24.6%. All those morphology data account for the superior optoelectronic performance of our SWCNT TCFs.

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Section: Resultsmentioning

confidence: 99%

High-performance single-walled carbon nanotube transparent conducting film fabricated by using low feeding rate of ethanol solution

Ding¹,

Zhang²,

Wei³

et al. 2018

R. Soc. open sci.

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“…Among the different synthesis methods, floating catalyst chemical vapor deposition (FCCVD) is an easily-scalable, one-step, continuous technique which has already been adopted by several companies [8]. This process involves the simultaneous injection of hydrocarbon and catalytic precursors into a reactor at temperatures ranging from 800 to 1200 °C in a reducing atmosphere [9,10]. Ferrocene is one of the most commonly used catalytic sources due to its good stability, low cost and non-toxicity [11].…”

Section: Introductionmentioning

confidence: 99%

Control of product nature and morphology by adjusting the hydrogen content in a continuous chemical vapor deposition process for carbon nanotube synthesis

Dichiara

et al. 2016

Carbon

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Floating catalyst chemical vapor deposition (FCCVD) is commonly considered as one of the most attractive process for the production of carbon nanotubes (CNTs). Understanding the phenomena occurring during the FCCVD synthesis of CNTs is critical to improve the process selectivity and scalability. The present work correlates information on gas chemistry and structural characteristics of the carbonaceous products, and show how both are strongly related to the hydrogen content in the reactor. Hydrogen plays different roles in the CNT growth process whose contributions depend on the synthesis conditions. Its presence induces an augmentation in carbon supply by promoting the decomposition of hydrocarbon vapors into more reactive byproducts, and by serving as an activation agent for the dissociation of physisorbed hydrocarbons on the surface of catalyst particles. However, high hydrogen content can induce catalytic hydrogenation of carbon and lead to surface modification of CNTs. Hydrogen also interferes with the decomposition of catalytic precursors, thus influencing the size and availability of catalyst nanoparticles. As a result, the mean and core diameters, crystallinity of the graphene walls, and length of CNTs are greatly influenced by the hydrogen flow, which offers the possibility to tune the CNT properties in a very simple, yet efficient way.

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“…While the conventional substrate-based CVD can tune the nanotube diameters by precisely controlling the catalyst sizes, significant batch-to-batch variations remain a drawback. On the other hand, the floating catalyst chemical vapor deposition (FCCVD) [2,[15][16][17][18] technique is attracting attention from both academia and industry. With the appropriate choice of reactants, precise condition control, and continuous winding collection of the CNT aerogel, the FCCVD process could achieve flexibility in product forms (e.g., yarns, sheets) providing mass production potential [19].…”

Section: Introductionmentioning

confidence: 99%

Continuous Synthesis of Double-Walled Carbon Nanotubes with Water-Assisted Floating Catalyst Chemical Vapor Deposition

et al. 2020

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Double-walled carbon nanotubes (DWCNTs) were synthesized and continuously collected using a water-assisted floating catalyst chemical vapor deposition (FCCVD) method. Differing from the conventional water-assisted synthesis in which water vapor is one part of the carrier gas mixture, we included de-ionized water in the catalyst system, which achieved a more uniform and controlled distribution for efficient DWCNT production. Using a water-assisted FCCVD process with optimized conditions, a transition from multi- to double-walled CNTs was observed with a decrease in diameters from 19–23 nm to 10–15 nm in tandem with an elevated Raman IG/ID ratio up to 10.23, and corroborated from the decomposition peak shifts in thermogravimetric data. To characterize the mechanical and electrical improvements, the FCCVD-CNT/bismaleimide (BMI) composites with different water concentrations were manufactured, revealing high electrical conductivity of 1720 S/cm along the bundle alignment (collection) direction, and the nano-indentation tests showed an axial reduced modulus at 65 GPa. A consistent value of the anisotropic ratio at ~3 was observed comparing the longitudinal and transverse properties. The continuous capability of the presented method while maintaining high quality is expected to result in an improved DWCNT mass production process and potentially enhance the structural and electrical applications of CNT nanocomposites.

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The effect of a convection vortex on sock formation in the floating catalyst method for carbon nanotube synthesis

Cited by 57 publications

References 29 publications

High-performance single-walled carbon nanotube transparent conducting film fabricated by using low feeding rate of ethanol solution

High-performance single-walled carbon nanotube transparent conducting film fabricated by using low feeding rate of ethanol solution

Control of product nature and morphology by adjusting the hydrogen content in a continuous chemical vapor deposition process for carbon nanotube synthesis

Continuous Synthesis of Double-Walled Carbon Nanotubes with Water-Assisted Floating Catalyst Chemical Vapor Deposition

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