Diameter-Controlled Synthesis of Carbon Nanotubes

Cheung, Chin Li; Kurtz, Alton C.; Park, Hongkun; Lieber, Charles M.

doi:10.1021/jp0142278

Cited by 762 publications

(587 citation statements)

References 24 publications

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“…Traditionally, the most common route to achieve high chiral selectivity is through control of catalyst size due to the reported correlation between catalyst size and resulting nanotube diameter [8][9][10]. For catalyst of similar size, we have previously shown the chemical composition M x 1 M y 2 of binary metal oxide nanoparticles has a significant control over the range of chiralities grown [11].…”

Section: Introductionmentioning

confidence: 99%

Understanding the “Activation” of the Nanocluster [HxPMo12O40⊂H4Mo72Fe30(O2CMe)15O254(H2O)98-y(EtOH)y] for Low Temperature Growth of Carbon Nanotubes

Esquenazi

Barron

2018

J Clust Sci

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(FeMoC), was the first molecular catalyst precursor (pro-catalyst) that promised controlled growth of carbon nanotubes (CNTs); however, temperatures in excess of * 900°C or the addition of excess iron were required as catalyst promoters for CNT growth. To understand these disappointing results the ''activation'' of FeMoC for CNT growth was studied by systematic investigation of H 2 gas concentration and growth temperature. The pathway for ''activation'' of FeMoC occurs through the sufficient reduction of both metal oxide components in the pro-catalyst. By ensuring pro-catalyst reduction prior to introduction of growth gases, we demonstrate for the first time, growth of CNTs at temperatures as low as 600°C without the use of catalyst promoters using the single molecular precursor, FeMoC. To understand the role of catalyst promoters used in prior work, thermogravimetric analysis experiments were performed. The addition of an iron catalyst promoter is observed to play two key roles in the ''activation'' of FeMoC: (1) to replenish sublimated metal atoms, and (2) to reduce the reduction temperature required for reduction of FeMoC into an ''active'' catalyst. These results caution the conditions employed in many earlier studies for CNT growth, and create new possibilities for molecular pro-catalysts.

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Section: Introductionmentioning

confidence: 99%

Understanding the “Activation” of the Nanocluster [HxPMo12O40⊂H4Mo72Fe30(O2CMe)15O254(H2O)98-y(EtOH)y] for Low Temperature Growth of Carbon Nanotubes

Esquenazi

Barron

2018

J Clust Sci

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“…This condition is due to nanoparticles activated by their diameter under a given carbon feeding rate where large particles are underfed and not nucleating growth, while smaller particles are cutoff from carbon supplies in consequence of carbon poisoning. [29,30] In this work, Co catalyst has a better role in growing CNTs as compared with Ni due to the effect of catalytic activity. The growth rate of nanotube appears to be more prominent in Co catalyst due to broader particle size distribution that allows further absorption of carbon feedstock, thereby resulting in a much thicker nanotube formation and higher growth rate.…”

Section: Resultsmentioning

confidence: 96%

Effect of Co and Ni nanoparticles formation on carbon nanotubes growth via PECVD

Lee

Haniff

Teh

et al. 2015

Journal of Experimental Nanoscience

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The effect of cobalt (Co) and nickel (Ni) nanoparticle catalysts on the growth of carbon nanotubes (CNTs) were studied, where the CNTs were vertically grown by plasma enhanced chemical vapour deposition (PECVD) method. The growth conditions were fixed at a temperature of 700 C with a pressure of 1000 mTorr for 40 minutes with various thicknesses of sputtered metal catalysts. Only multiwalled carbon nanotubes are present from the growth as large average diameter of outer tube (»10À30 nm) were measured for both of the catalysts used. Experimental results show that high density of CNTs was observed especially towards thicker catalysts layers where larger and thicker nanotubes were formed. The nucleation of the catalyst with various thicknesses was also studied as the absorption of the carbon feedstock is dependent on the initial size of the catalyst island. The average diameter of particle size increases from 4 to 10 nm for Co and Ni catalysts. A linear relationship is shown between the nanoparticle size and the diameter of tubes with catalyst thicknesses for both catalysts. The average growth rate of Co catalyst is about 1.5 times higher than Ni catalyst, which indicates that Co catalyst has a better role in growing CNTs with thinner catalyst layer. It is found that Co yields higher growth rate, bigger diameter of nanotube and thicker wall as compared to Ni catalyst. However, variation in Co and Ni catalysts thicknesses did not influence the quality of CNTs grown, as only minor variation in I G /I D ratio from Raman spectra analysis. The study reveals that the catalysts thickness strongly affects not only nanotube diameter and growth rate but also morphology of the nanoparticles formed during the process without influencing the quality of CNTs.

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“…For example, Lieber et al recently reported on the synthesis of SWNTs from pre-made mono-MNPs. 43 No structural information was available on those mono-MNPs. They found that only a small number of the nanoparticles participated in the catalytic process.…”

Section: Results On Other Mono Systemsmentioning

confidence: 99%

“…Other results have also confirmed that monodisperse MNPs are catalytically unequal. 43,45 It is unclear based on the current studies as to what is the key to the initiation of SWNT growth. Some catalysts are capable of producing SWNTs, while others are not.…”

Section: Discussionmentioning

confidence: 96%

Multifunctional Catalysts for Singlewall Carbon Nanotube Synthesis

Guo

2004

ChemInform

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Diameter-Controlled Synthesis of Carbon Nanotubes

Cited by 762 publications

References 24 publications

Understanding the “Activation” of the Nanocluster [HxPMo12O40⊂H4Mo72Fe30(O2CMe)15O254(H2O)98-y(EtOH)y] for Low Temperature Growth of Carbon Nanotubes

Understanding the “Activation” of the Nanocluster [HxPMo12O40⊂H4Mo72Fe30(O2CMe)15O254(H2O)98-y(EtOH)y] for Low Temperature Growth of Carbon Nanotubes

Effect of Co and Ni nanoparticles formation on carbon nanotubes growth via PECVD

Multifunctional Catalysts for Singlewall Carbon Nanotube Synthesis

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