Carbon nanotubes by catalytic decomposition

Gao, X.P., Qin, X., and Wu, F. (2000) Synthesis of carbon nanotubes by catalytic decomposition of methane using LaNi5 hydrogen storage alloy as a catalyst, Chem. Phys. Lett., 327, 271-276. 

C. W. Park, C. Y. Lee, C. J. Synthesis of Single- and Double-Walled Carbon Nanotubes by Catalytic Decomposition of Methane. Chem. Phys. Lett. 2003, 373, 475-479. 

J F Colomer, Syntfaesis of sii le-wall carbon nanotubes by catalytic decomposition of hydrocarbons , Chem. Conmun, 1999. 

Kitiyanan, B., Alvarez, W.E., Harwell, J.H., and Resasco, D.E. (2000) Controlled production of single-wall carbon nanotubes by catalytic decomposition of CO on bimetalhc Co-Mo catalysts. Chem. Phys. Lett., 317, 497-503. 

Pham-Huu C, Keller N, Roddatis W, Mestl G, Schloegl R, Ledoux MJ. Large scale synthesis of carbon nanofibers by catalytic decomposition of ethane on nickel nanoclusters decorating carbon nanotubes. Phys Chem Chem Phys 2002 4 514-21. 

During the last years, several authors have reported the production of carbon nanotubes by the catalytic decomposition of hydrocarbons in the presence of metals[l-5]. More recently, carbon nanotubes were also found as by-products of arc-discharge[6] and hydrocarbon flame[7] production of fullerenes. 

Electronically conducting polymers (ECPs) such as polyaniline (PANI), polypyrrole (PPy) and po 1 y(3.4-cthy 1 cncdi oxyth iophcnc) (PEDOT) have been applied in supercapacitors, due to their excellent electrochemical properties and lower cost than other ECPs. We demonstrated that multi-walled carbon nanotubes (CNTs) prepared by catalytic decomposition of acetylene in a solid solution are very effective conductivity additives in composite materials based on ECPs. In this paper, we show that a successful application of ECPs in supercapacitor technologies could be possible only in an asymmetric configuration, i.e. with electrodes of different nature. 

Shin HC, Liu M, Sadanadan B, Rao AM. Electrochemical insertion of lithium into multi-walled carbon nanotubes prepared by catalytic decomposition. J Power Sources 2002 112 216-221. 

Carbon Nanotubes Synthesis by Catalytic Decomposition of Hydrocarbons... 

Boron nitride nanotubes have been obtained by striking an electric arc between HfB, electrodes in a N2 atmosphere" BCN and BC nanotubes are obtained by arcing between B/C electrodes in an appropriate atmosphere A greater effort has gone into the synthesis of BN nanotubes starting with different precursor molecules containing B and N. Decomposition of borazine in the presence of transition metal nanoparticles and the decomposition of the I 2 melamine-boric acid addition compound yield BN nanotubes. Reaction of boric acid or B2O, with N2 or NH, at high temperature in the presence of activated carbon, carbon nanotubes or catalytic metal particles has been employed to synthesize BN nanotubes. ... 

Fig. 16. SEM (a) and TEM (b) images of multi-walled carbon nanotubes prepared by catalytic decomposition of acetylene on a Co Mgd.xfi solid solution [8J. Reprinted with permission from E. Baymundo-Pihero, K Khomenko, E. Frackawiak and F. Biguin, J Electrochem. Soc., 152 (2005) A229...

The fraction that precipitated on the bottom included nanotubes but there were mainly clusters. The N-3 sample was prepared by catalytic decomposition of xylene CgHio used as a carbon soxirce and ferrocene Fe(C5H5)2 as a catalyst precursor. 

M. Perez-Cabero, I. Rodrfguez-Ramos, and A. Guerrero-Ruiz, Characterization of Carbon Nanotubes and Carbon Nanofibers Prepared by Catalytic Decomposition of Acetylene in a Fluidized Bed Reactor, J. Catal., 215, pp. 305-16, 2003. 

Cheng, H.M. Li, F. Sun, X. Brown, S.D.M Pimenta, M.A. Marucci, A. Dresselhaus, G. Dresselhaus, M.S. (1998). Bulk morphology and diameter distribution of single-walled carbon nanotubes synthesized by catalytic decomposition of hydrocarbons. Chemical Physics Letters, 289,602-610. 

From the observation of the early stage of nanotube production by the catalytic decomposition of acetylene, it is concluded that steric hindrance arising from the surrounding nanotubes, graphite, amorphous carbon, catalyst support and catalyst particle itself could force bending of the growing tubules. 

The inner cavity of carbon nanotubes stimulated some research on utilization of the so-called confinement effect [33]. It was observed that catalyst particles selectively deposited inside or outside of the CNT host (Fig. 15.7) in some cases provide different catalytic properties. Explanations range from an electronic origin due to the partial sp3 character of basal plane carbon atoms, which results in a higher n-electron density on the outer than on the inner CNT surface (Fig. 15.4(b)) [34], to an increased pressure of the reactants in nanosized pores [35]. Exemplarily for inside CNT deposited catalyst particles, Bao et al. observed a superior performance of Rh/Mn/Li/Fe nanoparticles in the ethanol production from syngas [36], whereas the opposite trend was found for an Ru catalyst in ammonia decomposition [37]. Considering the substantial volume shrinkage and expansion, respectively, in these two reactions, such results may indeed indicate an increased pressure as the key factor for catalytic performance. However, the activity of a Ru catalyst deposited on the outside wall of CNTs is also more active in the synthesis of ammonia, which in this case is explained by electronic properties [34]. 

An exhaustive study has been carried out recently on the synthesis of BN nanotubes and nanowires by various CVD techniques.17 The methods examined include heating boric acid with activated carbon, multi-walled carbon nanotubes, catalytic iron particles or a mixture of activated carbon and iron particles, in the presence of ammonia. With activated carbon, BN nanowires are obtained as the primary product. However, with multi-walled carbon tubes, high yields of pure BN nanotubes are obtained as the major product. BN nanotubes with different structures were obtained on heating boric acid and iron particles in the presence of NH3. Aligned BN nanotubes are obtained when aligned multi-walled nanotubes are used as the templates (Fig. 40). Prior to this report, alignment of BN nanotubes was achieved by the synthesis of the BN nanotubule composites in the pores of the anodic alumina oxide, by the decomposition of 2,4,6-trichloroborazine at 750 °C.116 Attempts had been made earlier to align BN nanotubes by... 

In the elementary reactions of the pyrolysis, the atomic carbon is formed first. Then it transforms into the final product, whether it be soot, graphite, carbon nanofibers, or so forth. Why does the presence of catalysts make it possible to grow carbon nanofibers or nanotubes instead of soot In many cases, this is the so called carbide cycle that is characteristic of the catalytic process of hydrocarbon pyrolysis that is responsible for the growth of the elongated structures but not soot particles. The primary car bon atoms produced by pyrolytic decomposition of the hydrocarbon molecules are dissolved in the metal particle of the active catalyst compo nent to form a nonstoichiometric carbide (the carbon solution in the... 

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