Colloidal Solution of Metal Nanoparticles as a Catalyst for Carbon Nanotube Growth
- PDF / 2,504,018 Bytes
- 5 Pages / 595 x 842 pts (A4) Page_size
- 101 Downloads / 182 Views
Colloidal Solution of Metal Nanoparticles as a Catalyst for Carbon Nanotube Growth Hiroki Ago, Satoshi Ohshima, Toshiki Komatsu,1 Yasunori Kuriki, and Motoo Yumura National Institute of Materials and Chemical Research (NIMC), Tsukuba 305-8565 Japan 1Fine Ceramics Center (JFCC), 2-4-3 Nishi-Shinbashi, Tokyo, 105-0003 Japan ABSTRACT Aligned multi-wall carbon nanotubes (MWNTs) were successfully grown on a Si substrate based on a thermal chemical vapor deposition (CVD) method. We employed Co metal nanoparticles as the catalyst for nanotube growth, which were prepared by a reverse micelle method. The reverse micelle method provides nanoparticles covered with surfactants so that they are dispersed in organic solvent and, thus highly processible. The present MWNT arrays are promising for application in field emission displays, because of much lower nanotube density compared with the previously reported arrays. INTRODUCTION As a method to synthesize carbon nanotubes, chemical vapor deposition (CVD) method in the presence of a transition metal catalyst has attracted a great interest. This is because the CVD proceeds at relatively lower temperature (below 1000 °C) with less carbon impurities and gives much larger quantities compared with other methods [1]. Moreover, the catalytic CVD method offers a new route to control over the alignment and/or direction of carbon nanotubes. Metal nanoparticles are essential for the growth of carbon nanotubes in the CVD method, because they act as a catalyst of the nanotube growth; the size and chemical composition of the metal nanoparticle determines diameter and structural perfection of the nanotube. Metal nanoparticles employed in the CVD reaction have been realized mainly by the following two approaches; incorporation of metals into pores of nanoporous materials such as zeolites [2] and porous silicon [3], and etching metal substrates by laser-beam [4] or plasma treatment [5]. For future development, a more simple synthetic method applicable to non-porous and large area substrates is very important. In this paper, we show that metal nanoparticles chemically synthesized by a reverse micelle method catalyzes the growth of multi-wall carbon nanotubes (MWNTs) [6]. We show that straight and aligned multi-wall carbon nanotubes (MWNTs) grew from the . nanoparticles pretreated with hydrogen disulfide (H2S) on a plane Si substrate.
EXPERIMENTAL In our reverse micelle method, cobalt chrolide is reduced in a nanoscale water pool surrounded by surfactants to form the metal nanoparticle stabilized by the surfactants. We A13.18.1
Figure 1. TEM images of Co nanoparticles cast on polymer-coated TEM grids. Depending on concentrations in the solution, nanoparticles with average diameters of 4 nm (a) and 14 nm (b) were prepared. Due to the presence of surfactants, the nanoparticles are apart with a certain distance.
employed didodecyldimethylammonium bromide (DDAB) and sodium borohydride The details are (NaBH4) as the cationic surfactant and reducing agent, respectively. described elsewhere [6]. The ca
Data Loading...
