2006
DOI: 10.1016/j.chemphys.2006.05.015
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Theoretical calculations on the catalytic growth of multiwall carbon nanotube in chemical vapor deposition

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Cited by 15 publications
(5 citation statements)
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References 29 publications
(23 reference statements)
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“…Nevertheless, currently available models do provide some insight into the mechanisms that control CNT growth. The kinetic model of Kamachali predicts a CNT growth activation barrier very close to the observed barrier and explains this barrier as the sum of the activation energies for carbon dissolution in and diffusion through the metal catalyst. The model of Puretzky et al .…”
Section: Discussionmentioning
confidence: 68%
“…Nevertheless, currently available models do provide some insight into the mechanisms that control CNT growth. The kinetic model of Kamachali predicts a CNT growth activation barrier very close to the observed barrier and explains this barrier as the sum of the activation energies for carbon dissolution in and diffusion through the metal catalyst. The model of Puretzky et al .…”
Section: Discussionmentioning
confidence: 68%
“…According to the vapor–liquid–solid (VLS) model, the carbon feedstock is catalytically decomposed by the catalyst particles at elevated temperature, after which it dissolves into the catalyst, before finally forming CNTs when the carbon reaches supersaturation . The distribution of active sites on the catalyst particle surface determines the CNT length, diameter and alignment . Uniform catalyst activity is known to play an important role in the growth of aligned CNT arrays and previous studies suggest that the CNT growth is primarily driven by the carbon concentration gradient in the catalyst particle. , During the stable stage of CNT growth, where carbon dissolution and precipitation rates are in equilibrium, the concentration gradient in the catalyst does not change with growth time, resulting in CNTs that are straight and relatively defect free.…”
Section: Resultsmentioning
confidence: 99%
“…The distribution of active sites on the catalyst particle surface determines the CNT length, diameter and alignment . Uniform catalyst activity is known to play an important role in the growth of aligned CNT arrays and previous studies suggest that the CNT growth is primarily driven by the carbon concentration gradient in the catalyst particle. , During the stable stage of CNT growth, where carbon dissolution and precipitation rates are in equilibrium, the concentration gradient in the catalyst does not change with growth time, resulting in CNTs that are straight and relatively defect free. It has been suggested, that except for islands of catalyst optimal for CNT growth, small particles may lose CNT growth activity as a result of the overfeeding effect, where Ostwald ripening minimizes surface energy and small catalyst particles coalesce into larger particles.…”
Section: Resultsmentioning
confidence: 99%
“…(4) corresponds to the following sequence of elementary steps, which consists of equilibrated adsorption of ethylene and of the irreversible surface ethylene decomposition as the ratedetermining step [34]: Activation energy E 2 was found to be equal to around 120 ± 15 kJ mol −1 , standard adsorption enthalpy H • to around −120 ± 20 kJ mol −1 , and standard adsorption entropy S • to around −120 ± 20 J mol −1 K −1 . As a comparison with previous literature, reported activation energies for ethylene decomposition into carbon nanotubes and hydrogen vary between 100 kJ mol −1 and 180 kJ mol −1 , depending on the catalyst nature [28,[34][35][36][37], while reported ethylene adsorption enthalpies with different catalyst vary from −160 kJ mol −1 to −60 kJ mol −1 [28,38,39]. Let us mention that ethylene adsorption enthalpy and entropy, H • and S • , must verify thermodynamic constraints.…”
Section: Kinetic Studymentioning
confidence: 98%