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The synthesis of vertically aligned multi-walled carbon nanotube forests by thermal chemical vapor deposition

M. Chang ; P. Yaghoobi ; Waqas Khalid (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; A. Nojeh
Carbon Nanotubes: Synthesis and Properties p. 9-23. (2012)
[Kapitel]

Despite the many potential applications and attractive characteristics of carbon nanotubes (CNTs), a major challenge on the way toward their commercialization remains their controlled synthesis. In this chapter, we present a parametric study of the synthesis of vertically-aligned CNT forests using an ethylene-based chemical vapor deposition system without any oxidizing agent. We also provide an overview of the complex effects of hydrogen and an interpretation of the non-monotonic effect of the hydrogen flow rate on the resulting carbon nanotube forests. Even though hydrogen plays a partial role as a carrier gas (other than acting as a reducing agent), variations in the hydrogen and argon flow rates lead to distinct trends in the synthesis outcome, pointing to the diverse roles for the reducing and carrier gases: adjusting the proportions of hydrogen and argon for a given total flow rate had a drastic impact. The gas flow profile was optimal at an ethylene-to-total flow ratio of 8% and ethylene-to-hydrogen ratio of 25%, respectively. A strong temperature dependence was also observed: while the growth was similarly successful at 675 C and 725 C, a temperature of 650 C led to severely suppressed yield. According to transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy analysis, the tip-growth mechanism dominates in this synthesis method.



Denna post skapades 2015-05-04.
CPL Pubid: 216350

 

Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Fysikalisk kemi (2005-2014)

Ämnesområden

Kemiteknik
Nanoteknik

Chalmers infrastruktur