Abstract:We report the mutually exclusive relationship between carbon nanotube (CNT) yield and crystallinity. Growth conditions were optimized for CNT growth yield and crystallinity through sequential tuning of three input variables: growth enhancer level, growth temperature, and carbon feedstock level. This optimization revealed that, regardless of the variety of carbon feedstock and growth enhancer, the optimum conditions for yield and crystallinity differed significantly with yield/crystallinity, preferring lower/hi… Show more
“…4c). In general, this opposing trend is in agreement with previous reports regarding the relation of G/D-ratio and yield 13 . One can conclude from these results that a carbon feedstock with high reactivity requires less input to synthesize a determined amount of CNTs which can result in higher G/D-ratios.Figure 4Comparisons of the SWCNT structure.(a) Raman G/D-ratio as a function of carbon feedstock concentration.…”
Section: Resultssupporting
confidence: 93%
“…The development of scientific research and industrial applications for carbon nanotubes (CNTs) has been primarily limited by its synthesis and as a result, immense research, encompassing the control of the structure and underlying growth mechanism, has been invested over the past two decades to improve growth control, e.g. efficiency 1,2,3,4,5,6,7,8 , crystallinity 9,10,11,12,13 and chirality 14,15 . Apt examples include the water-assisted chemical vapor deposition (CVD) method to improve growth efficiency 2 , floating catalyst CVD method to improve crystallinity 11 and catalyst gas pretreatments for metallic selective growth 14,15 .…”
We report the virtually infinite possible carbon feedstocks which support the highly efficient growth of single-wall carbon nanotubes (SWCNTs) using on the water-assisted chemical vapor deposition method. Our results demonstrate that diverse varieties of carbon feedstocks, in the form of hydrocarbons, spanning saturated rings (e.g. trans-deca-hydronaphthalene), saturated chains (e.g. propane), unsaturated rings (e.g. dicyclopentadiene), and unsaturated chains (e.g. ethylene) could be used as a carbon feedstocks with SWCNT forests with heights exceeding 100 ums. Further, we found that all the resultant SWCNTs possessed similar average diameter indicating that the diameter was mainly determined by the catalyst rather than the carbon feedstock within this synthetic system. A demonstration of the generality was the synthesis of a carbon nanotube forest from a highly unorthodox combination of gases where trans-decahydronaphthalene acted as the carbon feedstock and benzaldehyde acted as the growth enhancer.T he development of scientific research and industrial applications for carbon nanotubes (CNTs) has been primarily limited by its synthesis, and as a result, immense research, encompassing the control of the structure and underlying growth mechanism, has been invested over the past two decades to improve growth control, e.g. efficiency 1-8 , crystallinity 9-13 , and chirality 14,15 . Apt examples include the water-assisted chemical vapor deposition (CVD) method to improve growth efficiency 2 , floating catalyst CVD method to improve crystallinity 11 , and catalyst gas pretreatments for metallic selective growth 14,15 .Post-synthetic techniques have also been developed to improve the purity or selectivity of the CNTs. For example, density gradient ultracentrifugation combined with the appropriate surfactant enables effective individualization of single-wall carbon nanotube (SWCNT) for the separation of metallic versus semiconducting SWCNTs as well as the enrichment of a single-chirality, (6,5) 16 . In addition, numerous post-synthetic processes have been developed for the purification of CNTs ranging from chemical oxidation, such as gas phase, liquid phase, and electrochemical oxidation, to physical-based purification, such as filtration, centrifugation, functionalization, and high temperatures annealing and combinations [17][18][19] .In the synthesis of CNTs by the CVD process, numerous carbon feedstocks have been applied, often in the form of hydrocarbons, such as methane 20,21 , acetylene 20,29,30 , and ethylene 2,20 and even anthracene 21 . Further, each synthetic method, i.e. thermal CVD, plasma-enhanced CVD, floating catalyst CVD, laser ablation, seemed to show preferences on the carbon feedstock [22][23][24] . For example, in plasma-enhanced CVD, methane or other low molecular-weight carbon feedstocks are preferred 22 , while for floating catalyst CVD, which is carried out at higher temperatures, cyclic aromatic hydrocarbons, e.g. toluene, xylene, and benzene are most commonly used due to their high decomposi...
“…4c). In general, this opposing trend is in agreement with previous reports regarding the relation of G/D-ratio and yield 13 . One can conclude from these results that a carbon feedstock with high reactivity requires less input to synthesize a determined amount of CNTs which can result in higher G/D-ratios.Figure 4Comparisons of the SWCNT structure.(a) Raman G/D-ratio as a function of carbon feedstock concentration.…”
Section: Resultssupporting
confidence: 93%
“…The development of scientific research and industrial applications for carbon nanotubes (CNTs) has been primarily limited by its synthesis and as a result, immense research, encompassing the control of the structure and underlying growth mechanism, has been invested over the past two decades to improve growth control, e.g. efficiency 1,2,3,4,5,6,7,8 , crystallinity 9,10,11,12,13 and chirality 14,15 . Apt examples include the water-assisted chemical vapor deposition (CVD) method to improve growth efficiency 2 , floating catalyst CVD method to improve crystallinity 11 and catalyst gas pretreatments for metallic selective growth 14,15 .…”
We report the virtually infinite possible carbon feedstocks which support the highly efficient growth of single-wall carbon nanotubes (SWCNTs) using on the water-assisted chemical vapor deposition method. Our results demonstrate that diverse varieties of carbon feedstocks, in the form of hydrocarbons, spanning saturated rings (e.g. trans-deca-hydronaphthalene), saturated chains (e.g. propane), unsaturated rings (e.g. dicyclopentadiene), and unsaturated chains (e.g. ethylene) could be used as a carbon feedstocks with SWCNT forests with heights exceeding 100 ums. Further, we found that all the resultant SWCNTs possessed similar average diameter indicating that the diameter was mainly determined by the catalyst rather than the carbon feedstock within this synthetic system. A demonstration of the generality was the synthesis of a carbon nanotube forest from a highly unorthodox combination of gases where trans-decahydronaphthalene acted as the carbon feedstock and benzaldehyde acted as the growth enhancer.T he development of scientific research and industrial applications for carbon nanotubes (CNTs) has been primarily limited by its synthesis, and as a result, immense research, encompassing the control of the structure and underlying growth mechanism, has been invested over the past two decades to improve growth control, e.g. efficiency 1-8 , crystallinity 9-13 , and chirality 14,15 . Apt examples include the water-assisted chemical vapor deposition (CVD) method to improve growth efficiency 2 , floating catalyst CVD method to improve crystallinity 11 , and catalyst gas pretreatments for metallic selective growth 14,15 .Post-synthetic techniques have also been developed to improve the purity or selectivity of the CNTs. For example, density gradient ultracentrifugation combined with the appropriate surfactant enables effective individualization of single-wall carbon nanotube (SWCNT) for the separation of metallic versus semiconducting SWCNTs as well as the enrichment of a single-chirality, (6,5) 16 . In addition, numerous post-synthetic processes have been developed for the purification of CNTs ranging from chemical oxidation, such as gas phase, liquid phase, and electrochemical oxidation, to physical-based purification, such as filtration, centrifugation, functionalization, and high temperatures annealing and combinations [17][18][19] .In the synthesis of CNTs by the CVD process, numerous carbon feedstocks have been applied, often in the form of hydrocarbons, such as methane 20,21 , acetylene 20,29,30 , and ethylene 2,20 and even anthracene 21 . Further, each synthetic method, i.e. thermal CVD, plasma-enhanced CVD, floating catalyst CVD, laser ablation, seemed to show preferences on the carbon feedstock [22][23][24] . For example, in plasma-enhanced CVD, methane or other low molecular-weight carbon feedstocks are preferred 22 , while for floating catalyst CVD, which is carried out at higher temperatures, cyclic aromatic hydrocarbons, e.g. toluene, xylene, and benzene are most commonly used due to their high decomposi...
“…136,137 To make CNT forests competitive in each application space, targeted growth must advance to hone application-specific properties. Researchers have sought to focus control on one or a few critical characteristics including intrinsic CNT forest properties like crystallinity/defect density, 138,139 wall number, 140−142 diameter (and polydispersity), 143−148 alignment, 149 and areal density. 147,150 Importantly, there are inherent tradeoffs between these characteristics, which limit the extent of independent control and thus should be considered in the application design.…”
Section: Recent Advances In Swcnt Growthmentioning
Advances in the synthesis and scalable manufacturing of single-walled carbon nanotubes (SWCNTs) remain critical to realizing many important commercial applications. Here we review recent breakthroughs in the synthesis of SWCNTs and highlight key ongoing research areas and challenges. A few key applications that capitalize on the properties of SWCNTs are also reviewed with respect to the recent synthesis breakthroughs and ways in which synthesis science can enable advances in these applications. While the primary focus of this review is on the science framework of SWCNT growth, we draw connections to mechanisms underlying the synthesis of other 1D and 2D materials such as boron nitride nanotubes and graphene.
“…1) can be grown up to millimetre lengths, contain negligible catalytic impurities, and can now be produced commercially at up to the tonne-scale annually. 9 The diameter of SG-CNTs varies from 2-5 nm, controlled by the amount of catalyst deposited; below around 3 nm, as used in this study, the majority are single wall nanotubes. 10 As-synthesised, SWCNTs generally form bundles, due to their high surface energy, which are mechanically and electronically inferior to the ideal individualised species.…”
Long single-walled carbon nanotubes, with lengths >10 μm, can be spontaneously dissolved by stirring in a sodium naphthalide N,N-dimethylacetamide solution, yielding solutions of individualised nanotubide ions at concentrations up to 0.74 mg mL. This process was directly compared to ultrasonication and found to be less damaging while maintaining greater intrinsic length, with increased individualisation, yield, and concentration. Nanotubide solutions were spun into fibres using a new reactive coagulation process, which covalently grafts a poly(vinyl chloride) matrix to the nanotubes directly at the point of fibre formation. The grafting process insulated the nanotubes electrically, significantly enhancing the dielectric constant to 340% of the bulk polymer. For comparison, samples were prepared using both Supergrowth nanotubes and conventional shorter commercial single-walled carbon nanotubes. The resulting nanocomposites showed similar, high loadings (ca. 20 wt%), but the fibres formed with Supergrowth nanotubes showed significantly greater failure strain (up to ∼25%), and hence more than double the toughness (30.8 MJ m), compared to composites containing typical ∼1 μm SWCNTs.
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