In Situ TEM Observations on the Sulfur-Assisted Catalytic Growth of Single-Wall Carbon Nanotubes

Abstract

The effect of sulfur on the catalytic nucleation and growth of single-wall carbon nanotubes (SWCNTs) from an iron catalyst was investigated in situ by transmission electron microscopy (TEM). The catalyst precursor of ferrocene and growth promoter of sulfur were selectively loaded inside of the hollow core of multiwall CNTs with open ends, which served as a nanoreactor powered by applying a voltage inside of the chamber of a TEM. It was found that a SWCNT nucleated and grew perpendicularly from a region of the catalyst nanoparticle surface, instead of the normal tangential growth that occurs with no sulfur addition. Our in situ TEM observation combined with CVD growth studies suggests that sulfur functions to promote the nucleation and growth of SWCNTs by forming inhomogeneous local active sites and modifying the interface bonding between catalysts and precipitated graphitic layers, so that carbon caps can be lifted off from the catalyst particle.

In situ insight into the unconventional ruthenium catalyzed growth of carbon nanostructures

“…7 To control and to optimize the growth and the subsequent properties of carbon nanostructures, crucial questions should be answered for which several in situ experiments and theoretical studies have been performed dealing with various nanoparticle catalysts (Ni, Fe, Au, Co, Pd, Ru, etc.). [8][9][10][11][12][13][14][15] What is the state (crystalline, liquid, fluctuating crystalline) and the nature of the active phase (carbide or metallic) of these nanoparticles? Do carbon atoms migrate on the surface and/or through the bulk of the nanoparticles?…”

Nitrogen controlled iron catalyst phase during carbon nanotube growth

“…2,4,[62][63][64][65][66] In this context, e.g., we have recently shown that the addition of NH 3 to the pretreatment atmosphere for SWNT CVD narrows and downshifts diameter and chiral distributions in cobalt-catalyzed SWNT growth. 4 In line with our current observations, we argued that this was related to nitrogen-induced changes in the cobalt catalyst structure/faceting, which translate to a change in nucleating SWNT chiralities.…”

Microwave-induced electric discharges on metal particles for the synthesis of inorganic nanomaterials under solvent-free conditions

“…It is well established that sulfur acts as a growth promoter for carbon nanotubes and carbon fibers [ 20 – 21 ]. Thus, sulfur was introduced to the reaction mixtures to improve the yield of nanorods.…”