The effects of atmospheric pressure plasma on the synthesis of carbon nanotubes

In this study, we investigated the effects of atmospheric plasma on the synthesis of carbon nanotubes (CNTs) forests. Tall and high CNTs forests have been successfully grown on a large scale using a newly developed system called atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD). By introducing atmospheric pressure plasma to facilitate the dissociation capability of carbon source gas, the growth rate and height of CNTs forests dramatically increased up to six times compared to that of forests grown thermally and with low plasma power chemical vapor deposition. At a plasma power of 40 W, the height of CNTs forests was 267 mu m after 3 min of growth, which corresponds to a growth rate of 89 mu m/min. The resultant high growth rate means that high-power plasma can contribute to dissociate C-H bonding in carbon source gas. By using AP-PECVD, multi-walled and some single-walled CNTs were also grown. These CNTs displayed almost no amorphous carbon and very few defects, as observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Our study allows for the possibility of large scale production of CNTs at a low cost in atmospheric pressure ambient for commercial use, especially with regard to reinforcing material with polymer and ceramic matrices. (C) 2009 Elsevier B.V. All rights reserved.