使用釤鈷鹽為催化劑以電弧放電法製備 奈米碳管

Fabrication of Carbon Nanotubes Using Arc-Discharge System with Samarium-Cobalt Catalyst

陳正雄(Jeng-shiung Chen)

指導教授 ： 蔡宗惠

大同大學/電機資訊學院/光電工程研究所/碩士(2006年)

摘要

本實驗的主要目的為使用釤鈷鹽催化劑以電弧放電法製備奈米碳管。我們使用自行設計與組裝的電弧放電系統。由於釤鈷鹽催化劑是首次被應用於電弧放電技術成長奈米碳管，因此其成長奈米碳管之效能亦於本實驗中得到驗證。經由一系列的實驗，我們也得到實驗之優化參數。透過電子顯微鏡的觀察，我們觀察到多層奈米碳管的生成。我們使用商用多層碳管作為碳源，進而以優化參數條件下產生層數較少的奈米碳管。
在使用釤鈷鹽催化劑的狀況下，大部分的產物皆可量測到拉曼(Raman)光譜中的徑向呼吸模式(Radial Breathing Mode, RBM)。一般而言，此徑向呼吸模式是單層奈米碳管所特有的特徵訊號，或由極少層壁並較大直徑之多層奈米碳管所引發之頻譜。然而藉由穿透式電子顯微鏡的觀察，我們發現到其產物多數為多層奈米碳管且具有良好的石墨化結構和不具有竹節狀的缺陷。此觀察結果也呼應拉曼光譜的正切模式中，G-band 與D-band的高強度比值(~88)。但是我們所發現到的多層奈米碳管並不會產生徑向呼吸模式。因而我們推測所量測的徑向呼吸模式應是由單層奈米碳管所產生的，但因其產率過低以致難以在穿遂式電子顯微鏡中被觀察到。
在我們的實驗中，使用釤鈷鹽催化劑所成長的奈米碳管皆具有良好的石墨化結構，且在碳管內部並無催化劑粒子的形成。實驗的結果顯示運用釤鈷鹽為催化劑之電弧放電技術，是適用於成長高品質的奈米碳管的創新製程。

關鍵字

奈米碳管 ； 電弧放電

並列摘要

In this thesis, the carbon nanotubes (CNTs) was fabricated by arc-discharge method with the samarium-cobalt (Sm-Co) chloride as the catalyst. The experimental apparatus was designed and assembled by ourselves. The Sm-Co chloride was first applied as catalyst for CNT formation. The optimized recipes were also determined by a series experiments. By the TEM observations, we observed the main products are multi-walled carbon nanotubes (MWCNTs). We also used the commercial MWCNTs to serve as carbon sources and fabricated the MWCNT with less tube walls. With the assistance of the Sm-Co chloride catalyst, the radial breathing modes (RBMs) of the Raman spectra were measured. Generally, the RBM only belongs to the characteristic Raman signals of single-walled carbon nanotubes (SWCNTs) or induced by the thin MWCNTs with large outer diameter. The tunneling electron microscopy (TEM) observations revealed our nanotubes are mainly multi-walled. These tubes have good graphitic structures and less bamboo defects which agree with their Raman measurements with high IG/ID ratio (~88). The IG and ID are the intensity of the tangential modes (TMs) of the Raman spectra. These tubes were unlikely to generate RBMs due to the observation from TEM which the thick MWCNT were mainly found. We believe that the product from our arc-discharge system contain few SWCNTs which give RBMs. However, the quantity of these SWCNTs may be too low to be observed by TEM. In our experiments, the CNTs fabricated using Sm-Co chloride catalyst exhibited good quality in structure. Our CNTs have no catalyst particles encapsulated inside the tube which is the advantage using such catalyst to fabricate CNTs. Compare to the MWCNTs fabricated from chemical vapor deposition (CVD) which usually have bamboo defects and catalyst encapsulations. The results of our experiments show that it is an unique approach to grow high quality CNTs.

並列關鍵字

carbon nanorubes ； arc-dsicharge

參考文獻

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