Diameter- and length-dependent self-organizations of multi-walled carbon nanotubes on spherical alumina microparticles

He, Delong; Bozlar, Michael; Genestoux, Maxime; Bai, Jinbo

doi:10.1016/j.carbon.2009.11.039

Cited by 64 publications

(38 citation statements)

References 45 publications

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“…Feed rates higher than 0.05mLmin À1 produce the ''sixbranch'' structures. [29] The length of the CNT bundles changes little (about 4 À 4.5 mm) with an increase in the solution feed rate. The same variation tendency is observed in the CNT number density.…”

Section: Influence Of Acetylene Concentrationmentioning

confidence: 99%

“…CNTs can either align perpendicularly on spherical surfaces, or organize into bundle-like structures. [11,13,29] An enhanced growth of single-walled CNTs by adding acetylene in ethanol CVD has recently been reported. [30] Our recent research has also demonstrated an improvement in CNT growth on a quartz plate by adding acetylene in floating CVD at 800 8C, [31] however a low temperature growth is greatly desired for CNT applications in electrical devices.…”

Section: Introductionmentioning

confidence: 99%

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Acetylene‐Enhanced Growth of Carbon Nanotubes on Ceramic Microparticles for Multi‐Scale Hybrid Structures

He¹,

Bai²

2011

Chemical Vapor Deposition

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A mixture of acetylene and xylene is used as the carbon source to directly synthesize carbon nanotube (CNT)/alumina (Al 2 O 3 ) microsphere hybrid structures by CVD. The hybrid structures are modulated by varying the acetylene ratio and reactor temperature. The addition of acetylene can significantly improve the CNT growth rate on Al 2 O 3 at temperatures lower than 600 8C. A tenfold improvement in CNT growth rate is obtained at 550 8C when only 2 vol.-% acetylene is added. Meanwhile, acetylene favors the formation of bundles containing high-density CNTs. The increase in the temperature promotes the formation of CNTs with large diameters and low number density. Mass spectrometry (MS) is used to investigate the decomposition of a mixture of acetylene/xylene at temperatures ranging from 450 to 700 8C, under the experimental conditions used. Acetylene decomposes with an increasing rate with temperature from 450 8C, however notable decomposition of xylene is not detected below 700 8C, which corresponds to the formation of the CNTs of varied diameters. This study demonstrates the possibility of large-scale production of desired nano/micrometer multifunctional CNT/Al 2 O 3 hybrid fillers using a gas/liquid mixed carbon source.

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Section: Influence Of Acetylene Concentrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Acetylene‐Enhanced Growth of Carbon Nanotubes on Ceramic Microparticles for Multi‐Scale Hybrid Structures

He¹,

Bai²

2011

Chemical Vapor Deposition

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“…%, tremendous improvement in the CNT yield could be observed. The efficiency of this floating catalyst method in enhancing the growth of CNTs was also reported previously on spherical micron silica gel [2], spherical alumina substrate [21], silica fibers [6], just to name a few. The particles synthesized via floating catalyst CVD were later selected for further electrical impedance investigation, as the condition with floating catalyst method yielded CNT with the high density ( figure 3).…”

Section: Synthesis and Characterization Of Pvoh -Cnt-fume Silicamentioning

confidence: 90%

The impedance characterization of Carbon Nanotubes - Fumed Silica Poly (vinyl alcohol) Composites

Othman

Wilkinson

2016

IOP Conf. Ser.: Earth Environ. Sci.

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Abstract. Carbon Nanotube (CNT) was grown on the surface of fumed silica via chemical vapor deposition (CVD) method. In this work, silica acted as a site that holds CNT together, which prevents further agglomeration during composite processing. Iron catalyst at different loading (7.5 wt. % up to 25 wt. %) was introduced via impregnation method to synthesize CNT at 1000°C, under methane flow. Floating catalyst method was used where ferrocene (2.5 wt. % and 5 wt. %) was used as starting reactants together with toluene at 760°C. The reaction time was set at 1 hour for both methods. It was later confirmed via SEM images that the floating catalyst method is more suitable to produce a large amount of CNTs. The sample synthesized via floating catalyst method at both 2.5 wt.% and 5 wt. % ferrocene was later used to prepare composites. Composite films of the particles in poly (vinyl alcohol) (PVOH) were cast and their TEM images show that the dispersion is indeed uniform. From impedance measurement, it was found that the particles synthesized via floating catalyst method were found to form an electrically-conductive percolated network with percolation threshold of 1 wt. %, obtained via percolation equation.

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“…To overcome these drawbacks, multi-walled carbon nanotubes (MWCNTs) have been directly grown on SiO 2 particles. He et al (2010) proved that the floating-catalyst chemical vapor deposition (FCCVD) technique can yield uniformly distributed CNTs on the SiO 2 surface, thereby reducing the chance of CNT aggregation. However, studies on gaseousphase treatment of CPCs over CNTs are few.…”

Section: Introductionmentioning

confidence: 99%

Influence of chlorine substitution on adsorption of gaseous chlorinated phenolics on multi-walled carbon nanotubes embedded in SiO2

Tulaphol

Bunsan²,

Kanchanatip

et al. 2016

Int. J. Environ. Sci. Technol.

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Multi-walled carbon nanotubes (MWCNTs) embedded in SiO 2 particles were prepared through the floating-catalyst chemical vapor deposition method. The parameters reaction time and flow rate of the carbon source (CH 4 ) were studied to obtain optimum conditions for MWCNT synthesis. The obtained MWCNTs were characterized by transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy to confirm their morphology and crystallinity. The optimum conditions were a CH 4 flow rate of 100 ml/min in a H 2 -Ar mixture at a flow rate of 500 ml/min and a reaction time of 20 min. Under these conditions, MWCNTs with average outer and inner diameters of around 50 and 10 nm, respectively, were obtained. SiO 2 particles with embedded MWCNTs were studied for their adsorption of gaseous chlorinated phenolic compounds (CPCs), with emphasis on the effect of number of chlorine substituents. The CPC compounds of 2-chlorophenol (CP) and 2,4-dichlorophenol (DCP) were compared against phenol (P). Adsorption of P and CPCs on the particles fit well the Langmuir isotherm. The adsorption capacities of P, CP, and DCP on SiO 2 particles with embedded MWCNTs were found to be 3.12, 13.83, and 44.25 mg/g, respectively. Desorption activation energy was determined by thermogravimetric analysis. Chlorine substitution on P changed the adsorption process from physical to chemical adsorption. The particles showed high potential for use as a pre-concentration unit for solid-phase microextraction.

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Diameter- and length-dependent self-organizations of multi-walled carbon nanotubes on spherical alumina microparticles

Cited by 64 publications

References 45 publications

Acetylene‐Enhanced Growth of Carbon Nanotubes on Ceramic Microparticles for Multi‐Scale Hybrid Structures

Acetylene‐Enhanced Growth of Carbon Nanotubes on Ceramic Microparticles for Multi‐Scale Hybrid Structures

The impedance characterization of Carbon Nanotubes - Fumed Silica Poly (vinyl alcohol) Composites

Influence of chlorine substitution on adsorption of gaseous chlorinated phenolics on multi-walled carbon nanotubes embedded in SiO2

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