Large-scale synthesis of aligned carbon nanotubes using FeCl3 as floating catalyst precursor

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 FeCl3 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.