The effects of hydrogen and temperature on the growth and microstructure of carbon nanotubes obtained by the Fe(CO)5 gas-phase-catalytic chemical vapor deposition

Kuo, Dong‐Hau; Su, Mei-Yun

doi:10.1016/j.surfcoat.2007.04.083

Cited by 16 publications

(7 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This observation agrees with earlier reports that nitrogen doping gets less probable with increasing temperatures 13 and the measured nitrogen content tendency. At higher temperatures the growth rate is in general higher, leading to more “normal” defects replacing the nitrogen induced defects 14. The Raman data confirms our conclusion.…”

Section: Resultssupporting

confidence: 88%

Ammonia assisted growth of multiwalled carbon nanotubes

Nitze¹,

Andersson²,

Wågberg³

2009

Physica Status Solidi (b)

View full text Add to dashboard Cite

Bamboo structured nitrogen-containing carbon nanotubes are grown on e-beam deposited thin metal films (cobalt/iron) by chemical vapor deposition. The approach uses ammonia as supporting gas to form nano catalyst particles in the pretreatment phase. Ammonia is also used as nitrogen source. The effect of ammonia on the grown structures at different temperatures (720 and 810 8C) is investigated by SEM, TEM and Raman spectroscopy. We show that ammonia promotes growth of vertically aligned CNT carpets on thicker metal films (5 nm) than usually used. At the same time ammonia is inducing a high amount of defects but this effect changes significantly with temperature. At 720 8C defects are clearly ammonia induced while at 810 8C the defects seem to be induced by a different mechanism. Furthermore, the presence of ammonia in both pretreatment phase and growth phase reduces the outer diameter of the grown nanotubes.

show abstract

Section: Resultssupporting

confidence: 88%

Ammonia assisted growth of multiwalled carbon nanotubes

Nitze¹,

Andersson²,

Wågberg³

2009

Physica Status Solidi (b)

View full text Add to dashboard Cite

show abstract

“…Therefore, samples A and B have a similar crystallinity. For sample C, as has been reported [20], CNTs growth at high- temperature was activated by the hydrogen input and became faster. The faster CNT growth affects the carbon arrangement into the wellcrystallized graphene sheets and produces folded graphene sheets with a higher I D /I G ratio.…”

Section: Resultssupporting

confidence: 70%

Effect of growth temperature on field emission from an array of carbon nanotubes nested into a silicon nanoporous pillar array

Jiang

Yang

et al. 2008

Thin Solid Films

View full text Add to dashboard Cite

“…14 Fe(CO) 5 is particularly used in preparation of carbon nanotubes via the catalytic chemical vapor deposition, where molecular hydrogen plays an important role in the growth and microstructure of nanotubes. 15 Iron carbonyls were detected in interstellar dust clouds and other extraterrestrial sources readily interacting with abundant present hydrogen molecules. 16 The binding of dihydrogen to organometallic complexes and its activation constitute fundamental steps in many catalytic mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Iron Carbonyl-Catalyzed Hydrogenation of Ethylene. 1. Theoretical Exploration of Molecular Pathways

Asatryan

Ruckenstein

2013

J. Phys. Chem. A

View full text Add to dashboard Cite

The hydrogenation of alkenes catalyzed by metal carbonyls is an intricate process involving reactions of various isomers of labile π- and σ-complexes, hydrides, dihydrides, and their radicals. Two general mechanisms have been suggested in the literature regarding the catalytic hydrogenation of simple alkenes by photochemically activated iron pentacarbonyl: a molecular mechanism that involves the sequential replacement of two carbonyl ligands by hydrogen and unsaturated ligands, and a radical mechanism involving the EPR-identified iron carbonyl hydride radicals. Even though significant results were obtained in numerous experiments and few theoretical studies, these mechanisms remain phenomenological, without detailed information regarding the potential energy surfaces (PES) and the elementary processes. Several major issues also remain open. It is still unclear, for instance, whether the ethane can be formed via a monomolecular reaction of ethyl hydride isomer intermediates HFe(CO)3(C2H5) or the only way to produce C2H6 is a bimolecular reaction assisted by a second ethylene. It is also uncertain if a dihydride or a dihydrogen complex is operating in olefin hydrogenation. To gain insight into these processes, a detailed theoretical examination of various PES for gas-phase reactions of ethylene with potential metallocomplex reagents to primary and secondary products (both singlet and triplet electronic states) was performed using DFT and ab initio methods. Calculations have been carried out for a set of reactions of ethylene with all possible isomers of tricarbonyliron hydrogenates, viz., dihydrides of trans-, cis-, and gauche-configurations (isomers with respect to the two hydridic atoms), and two nonclassical singlet and two triplet dihydrogen complexes, some of them being identified for the first time. The hydrogenation pathways (both molecular and radical) are shown to be strongly stereoselective and dependent on the spin configurations of the initial reagents. The combination of various dihydride isomers with C2H4 as separate reaction channels allowed us to explore relevant PES cross sections and to identify corresponding stereoregulated elementary processes. The reaction channels can alternatively start from the association of ethylene with dihydrogen tricarbonyliron complexes and may involve intersystem crossings with triplet pathways, followed by that of the corresponding singlet PES. Various interconversion and isomerization processes involving single-olefin adducts were found to precede the major ethane-elimination reactions (through both monomolecular and second-ethylene-assisted pathways). Monomolecular processes are suggested to occur under appropriate conditions. The stereospecific mechanistic results and thermochemical parameters constitute a basis for developing detailed kinetic models for iron-carbonyl catalysis.

show abstract

The effects of hydrogen and temperature on the growth and microstructure of carbon nanotubes obtained by the Fe(CO)5 gas-phase-catalytic chemical vapor deposition

Cited by 16 publications

References 32 publications

Ammonia assisted growth of multiwalled carbon nanotubes

Ammonia assisted growth of multiwalled carbon nanotubes

Effect of growth temperature on field emission from an array of carbon nanotubes nested into a silicon nanoporous pillar array

Mechanism of Iron Carbonyl-Catalyzed Hydrogenation of Ethylene. 1. Theoretical Exploration of Molecular Pathways

Contact Info

Product

Resources

About