Optical characterization of single-walled carbon nanotubes synthesized by catalyticdecomposition of alcohol

Shigeo Maruyama,Yuhei Miyauchi,Yoichi Murakami,Shohei Chiashi

doi:10.1088/1367-2630/5/1/149

Abstract

Single-walled carbon nanotubes (SWNTs), synthesized by a catalytic decomposition ofalcohol (alcohol CVD method, ACCVD), are compared with high-pressure CO (HiPco)SWNT samples through optical spectroscopic measurements such as resonant Ramanscattering, optical absorption and near infrared fluorescence. By the ACCVD method,SWNTs were synthesized either on zeolite catalyst-support particles or directly on thesurface of a quartz substrate; in the latter case, a simple dip-coat technique was employedfor mounting the metal catalyst. Specific morphological characteristics of as-grown SWNTsgenerated on zeolite support are presented using SEM and TEM, revealing that theSWNTs produced by the proposed method possess the significant quality of beingalmost free from amorphous carbons or metal particle impurities. The quality anddiameter distribution of SWNTs were investigated and discussed through the resultsof Raman scattering and optical absorption. The average diameter was slightlysmaller for SWNTs grown on zeolite particles than for HiPco SWNTs. Finally,fluorescent emission spectra from isolated SWNTs in an aqueous surfactant suspensionwere measured for various excitation wavelengths to determine the structural(n,m) distribution of the SWNTs. The narrower chirality distribution for ACCVD SWNTs grownon zeolite compared with HiPco SWNTs was demonstrated.

Highlights

The discovery of single-walled carbon nanotubes (SWNTs) [1] has invoked numerous research interests because of their unique physical properties [2] and remarkable potentials as a new material for vast possible applications
When this paper was in the final preparation stage, we found that Weisman et al [37] has measured the chirality distribution of SWNTs generated from the CCVD method of Resasco, which used the CO-disproportional reaction on Co/Mo catalyst supported on silica (CoMo CAT) [10]
The resonant Raman analyses with three different excitations 488, 514.5, and 633 nm were performed for alcohol catalytic CVD (ACCVD) SWNTs grown on zeolite and quartz substrates, and high-pressure CO (HiPco) SWNTs

Summary

Introduction

The discovery of single-walled carbon nanotubes (SWNTs) [1] has invoked numerous research interests because of their unique physical properties [2] and remarkable potentials as a new material for vast possible applications. The production technique of SWNTs has been sought from the earliest period to respond to strong demands for the specimen with sufficient amount and quality. Following to the landmark establishment of the synthesis method in macroscopic amount [3, 4], several techniques employing CVD approach [5,6,7,8,9,10,11,12,13,14,15,16,17,18] has been proposed for the improved efficiency or productivity in the bulk synthesis of SWNTs. At present, CVD approaches including the high-pressure CO (HiPco) technique [8, 12] have become dominant for the mass production of SWNTs. The present main issue concerning SWNTs production, is an enhancement of the quality that is critical for the reliable performance of proposed SWNT-based applications. The proposed alcohol catalytic CVD (ACCVD) method can produce SWNTs with fine quality when combined with appropriate catalysts and experimental procedures. It was recently demonstrated that high quality SWNTs could be synthesized on the mesoporous-silica coated substrate [21] or directly on solid substrate such as silicon and quartz [22]

Methods

Findings

Conclusion