Establishing the most favorable metal–carbon bond strength for carbon nanotube catalysts

Silvearv, Fredrik; Larsson, Peter; Jones, S. L.; Ahuja, Rajeev; Larsson, Andréas

doi:10.1039/c5tc00143a

Cited by 40 publications

(40 citation statements)

References 68 publications

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“…3a,b utilize CoMn and Co catalyst particles deposited on MCM41. Here, it is interesting to note that Mn is highly stable against reduction and does not act as a catalyst for SWNT growth (too large M-C bond strength) 49 , but instead acts in the alloy to prevent melting and evaporation of Co from the particles, thereby minimizing the effect of Ostwald ripening and agglomeration. This is the reason that the chirality distribution is less affected by temperature in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Chemical vapor deposition (CVD) has become the most promising technique for this purpose, since it involves several controllable growth parameters. The vapor-liquid-solid 43 44 45 (VLS) mechanism of fiber growth serves as a basis for understanding SWNT growth through catalytic-CVD, but one also has to account for the tubes being hollow: Since this results in an unstable growing end that has to be stabilized by a catalyst particle that has the metal–carbon binding energy in the required region–not too weak and not too strong, following a “Goldilocks” principle that is only fulfilled for a limited number of metals 46 47 48 49 , and can be tuned by alloying 50 51 . It has been shown that it is possible to affect the chirality of the growing SWNT by varying the experimental conditions, such as catalyst composition 12 14 15 16 52 53 54 55 temperature 56 , carbon precursor 10 17 , carrier gas pressure 57 , and catalyst support 11 18 .…”

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confidence: 99%

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On the Stability and Abundance of Single Walled Carbon Nanotubes

Hedman

Barzegar

Rosén

et al. 2015

Sci Rep

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Many nanotechnological applications, using single-walled carbon nanotubes (SWNTs), are only possible with a uniform product. Thus, direct control over the product during chemical vapor deposition (CVD) growth of SWNT is desirable, and much effort has been made towards the ultimate goal of chirality-controlled growth of SWNTs. We have used density functional theory (DFT) to compute the stability of SWNT fragments of all chiralities in the series representing the targeted products for such applications, which we compare to the chiralities of the actual CVD products from all properly analyzed experiments. From this comparison we find that in 84% of the cases the experimental product represents chiralities among the most stable SWNT fragments (within 0.2 eV) from the computations. Our analysis shows that the diameter of the SWNT product is governed by the well-known relation to size of the catalytic nanoparticles, and the specific chirality is normally determined by the product’s relative stability, suggesting thermodynamic control at the early stage of product formation. Based on our findings, we discuss the effect of other experimental parameters on the chirality of the product. Furthermore, we highlight the possibility to produce any tube chirality in the context of recent published work on seeded-controlled growth.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

On the Stability and Abundance of Single Walled Carbon Nanotubes

Hedman

Barzegar

Rosén

et al. 2015

Sci Rep

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“…The Goldilocks principle using the density functional theory‐based evaluation of the metal–carbon bond strength was proposed as a rational approach to evaluate the suitability of other metals as catalysts . The commonly implemented transition metals, Fe, Ni, and Co, have optimal bond strength to carbon, which makes them efficient catalysts for the growth of CNTs.…”

Section: Introductionmentioning

confidence: 99%

“…Metals like Mo and W feature high bond energy with carbon, which favors the formation of stable metal carbides. By contrast, metals like Cu, Au, and Pd have a too weak bond energy to stabilize the hollow structure of the CNT . The Goldilocks principle was further implemented to adjust the bond strength via the design of efficient alloys combining weakly and strongly bonding metals to carbon.…”

Section: Introductionmentioning

confidence: 99%

Low‐Temperature Thermal CVD of Superblack Carbon Nanotube Coatings

Basheer

Pachot

Lafont

et al. 2017

Adv Materials Inter

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The deposition of carbon nanotube (CNT) coatings via thermal chemical vapor deposition (CVD) is intensively reported. The surface acidity, chemical nature of the catalytic nanoparticles, and the carbon precursor are highly inter‐related key parameters. Furthermore, reducing the typical high‐growth temperature requires the implementation of toxic and hazardous organic precursors. In this study, the growth of CNT coatings is demonstrated using a single‐step CVD process in which magnesium oxides, material with enhanced basicity, and nanoparticles of cobalt are codeposited. This deposit catalyzes simultaneously the decomposition of ethanol to spark the growth of CNTs. The deposition is successively performed at 330–500 °C. Grown CNTs below 400 °C feature a high defect concentration and large diameters, 20 nm, relative to those obtained at ≥400 °C with no apparent defects and diameter of 12 nm. In terms of optical properties, films grown at ≥400 °C reflect less than 0.5% of light in the UV–vis–near IR, and exhibit a Lambertian behavior. Furthermore, the bidirectional reflectance distribution function measurements reveal identical optical properties irrespective of the underlying substrate. Therefore, the process holds a great potential for applications involving stray light reduction.

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“…The energy requirements for carbon nanotube growth with various nucleation metals has been explored using first principal Density Functional Theory using quantum espresso packaged with a generalized gradient approximation with Predew-Burke-Ernzerhof exchange-correlation functional using PAW pseudopotentials to identify the most energy efficient pathway for CNT growth, shown in Fig. 3 [9,17]. A CNT adsorbed onto a Ni cluster has the lowest energy state as a result of the strong metal-carbon adhesion bonds formed, while Zn has the highest energy state.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic assessment of CO2 to carbon nanofiber transformation for carbon sequestration in a combined cycle gas or a coal power plant

Lau

Dey

Licht

2016

Energy Conversion and Management

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a b s t r a c tMolten carbonate electrolyzers offer a pathway to capture emitted CO 2 from the flue gas of the power plants and transform this greenhouse gas emission at low energy and high yield instead into a specific, value added, hollow carbon nanofiber product, carbon nanotubes. The present day value of the carbon nanotubes product is $10,000 that of proposed, or in place, current carbon tax costs of $30 per ton, strongly incentivizing carbon dioxide removal. The recent progress in high-temperature molten carbonate electrolysis systems for carbon dioxide utilization and the impact these advances have on developing a CO 2 -free fossil fuel power plant for electricity generation is presented. A thermodynamic model analysis is presented for a molten Li 2 CO 3 electrolysis system incorporated within a combined cycle (CC) natural gas power plant to produce carbon nanofibers (CNF) and oxygen. Such a CC CNF plant system is shown to require 219 kJ to convert one mole of CO 2 to carbon, and generates electricity at higher efficiency due to pure oxygen looped back to the gas turbine input from the CO 2 splitting, with the added advantages that (i) the CC CNF plant emits no CO 2 and (ii) all CO 2 is converted to value added carbon nanotubes useful for strong, lightweight construction, batteries and nanoelectronics. Converting to power and ton units, per metric ton of methane fuel consumed the CC CNF plant is thermodynamically assessed to produce 8350 kW h of electricity and 0.75 ton of CNT and emits no CO 2 , while the CC plant produces 9090 kW h of electricity and emits 2.74 ton CO 2 . The required energy balance for a carbon nanotube production from an analogous coal power plant consumes a larger fraction of the coal energy, and encourages co-generation with renewable electric energy.

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Establishing the most favorable metal–carbon bond strength for carbon nanotube catalysts

Abstract: We have studied a wide range of transition metals to find potential carbon nanotube (CNT) catalysts for chemical vapor deposition (CVD) production.

Cited by 40 publications

References 68 publications

On the Stability and Abundance of Single Walled Carbon Nanotubes

On the Stability and Abundance of Single Walled Carbon Nanotubes

Low‐Temperature Thermal CVD of Superblack Carbon Nanotube Coatings

Thermodynamic assessment of CO2 to carbon nanofiber transformation for carbon sequestration in a combined cycle gas or a coal power plant

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