Large-Scale Synthesis of Aligned Carbon Nanotubes Using FeCl₃ as Floating Catalyst Precursor

Abstract

The continuous interest in carbon nanotubes (CNTs) and nanotube arrays has led us to discover new routes of high-yield and low-cost synthesis of CNTs with controlled tube structure. Here we show that a dilute solution of FeCl 3 in toluene and N,N-dimethylaminoacetate is a high-efficiency floating catalyst precursor in a chemical vapor deposition process. The growth structure and the self-assembling behavior of the resulting multiwall tubes was characterized using scanning and transmission electron microscopy. Clear indications are provided of the participation of iron carbide in the tube formation at higher temperatures. The characteristic cone-shaped morphology of the tubes is described in detail and discussed in terms of its interesting practical implications.

Heterogeneous hydroxylation catalyzed by multi-walled carbon nanotubes at low temperature

“…Nanotubes with concentric multi-walled layers of hexagonal carbon lattice display the same vibrations. The D-band at around 1360 cm À1 is associated with vibrations of carbon atoms with dangling bonds in plane terminations of disordered graphite or glassy carbons [13][14][15][16]. The two Raman spectra have almost the same pattern, implying that the reduction reaction does not affect the graphite structure of the MWCNTs.…”

The role of iron carbide in multiwalled carbon nanotube growth

“…In a previous paper, the occurrence of an iron carbide phase has been identified also in CNTs catalytically grown from iron(III)chloride at temperatures in the range 750- 1100 • C [31]. Another proof comes from the pyrolysis of ferrocene/anthracene precursor material [27].…”

“…The new graphene layers were preferentially segregated parallel to low-index lattice planes of the carbide which seems to be one reason for the rather frequent formation of polygonized MWCNT cross sections. On the other hand, the detection of cubic α-iron particles within CNTs after a low-temperature growth process [31] suggests that carbon does not necessarily form a carbide phase with the iron host. This issue, however, has not yet been cleared up under actual growth conditions.…”

Biocompatible, Hydrophilic, Supramolecular Carbon Nanoparticles for Cell Delivery

“…Graphene edge-plane surfaces have higher reactivities, but are typically eliminated in high-temperature synthesis through the formation of curved and closed structures that avoid the high-free-energy edges. Some catalytic routes produce extended edge-plane surfaces, [20][21][22] most notably platelet or herringbone nanofiber types (with perpendicular and tilted graphene layers, respectively) but at the cost of diminished strength and conductivity along the tube/fiber axis. In the sphere geometry there is no such disadvantage, and thus there is clear motivation for developing routes to "inverted-crystal-structure" nanoparticles with active surfaces.…”