Acetylene: A Key Growth Precursor for Single-Walled Carbon Nanotube Forests

Abstract

The growth of tall, single-walled carbon nanotube (SWNT) forests is often believed to require the use of specific feedstocks (e.g., ethanol) or etchants (e.g., water). Here, on the basis of mass spectrometry for hydrogendiluted methane in a microwave plasma-enhanced chemical vapor deposition (PECVD) reactor, we develop a purely thermal CVD process for SWNT forests without an etchant gas. The thermally grown SWNT forests are found to have a similar high quality, purity, growth rate, areal density, diameter, and chirality distribution as in the PECVD case. We show that C 2 H 2 is the main growth precursor, and suggest more generally that feedstock conversion to C 2 H 2 is of key importance to SWNT forest CVD. A reactive etchant, such as water, atomic hydrogen, or hydroxyl radicals, can widen the SWNT forest deposition window but is not required in cold-wall reactors at low pressures.Dense, vertically aligned forests of carbon nanotubes (CNTs) are being developed for a wide range of applications, such as interconnects in integrated circuits, thermal management systems, adhesive surfaces, supercapacitor electrodes, and microelectromechanical systems.

Investigating the plasma chemistry for the synthesis of carbon nanotubes/nanofibres in an inductively coupled plasma-enhanced CVD system: the effect of processing parameters

“…Moreover C 2 H 2 and C 2 H 4 decompose more easily at the catalyst surface than CH 4 at lower temperature [41]. Furthermore, C 2 H 2 [42]and C 2 H 4 [43] have been reported as key precursors for the efficient growth of SWCNTs by CVD. Bell et al [8] also confirmed that C 2 H 2 was the dominant precursor for CNT formation in a C 2 H 2 /NH 3 plasma.…”

Cross Sections for Electron Collisions with Acetylene

“…For example, plasma can be used to make HCCH from coal, 1 natural gas, 2 and methane. 3,4 Conversely acetylene plasmas are used for a variety of chemistries; 5 they are used to make C 2 , 6 CH*, 7 fullerenes, 8 diamonds, 9 carbon nanoparticles, 10 hydrocarbon nanoparticles, 11 nanotubes, 12,13 and polymers, 14 as well as other chemical processes. 15,16 Acetylene plasmas are used to provide a variety of different coatings.…”

Microstructural analysis of carbon nanomaterials produced from pyrolysis/combustion of Styrene-Butadiene-Rubber (SBR)

“…This indicates that they are instrumental in the formation process of carbon nanomaterials. Several previous investigations showed that LHCs generated in this work (benzene 21,22 , ethylene 23,24 , methane 18 , and acetylene 20 ) can be used as carbon feedstock in the production of nanomaterials. For example, when polyethylene was used as carbon feedstock for CNM SEM images show entangled nanomaterials which cover (not uniformly) the catalyst mesh under all conditions.…”

“…For TEM samples, the meshes were sonicated in a 100% ethanol solution and the products and without the catalyst system (the values are listed in parts per million -ppm). Several prior works have shown that the hydrocarbons can be used as important carbon donors in the production of CNMs using the catalytic CVD method [18][19][20][21][22][23][24] . The CCVD process used in this work basically consisted of thermal dehydrogenation reactions whereby a transition metal catalyst was used to "crack" the hydrocarbon gases into carbon and hydrogen 12 .…”