自製與商用奈米碳管材料之儲氫特性分析

Hydrogen Adsorption Properties of Commercial and As-Synthesized CNTs

張宇杉(Yu-Shan Chang)

指導教授 ： 王宏文

中原大學/理學院/奈米科技碩士學位學程/碩士(2010年)

https://doi.org/10.6840/cycu201000879

摘要

本實驗利用低壓化學蒸鍍奈米薄膜成長反應系統來成長多層奈米碳管，並採用固定的硝酸鐵溶液比例滴一滴於已沉積不同粒徑大小的Al2O3基板(1μm、0.3μm、0.1μm)，並探討氧化鋁基板薄膜對成長奈米碳管之影響。
本實驗中所採用的奈米碳管為日本生產，其純度為大於99.5%的多層奈米碳管(MWCNT)，碳管直徑分布為50-100 nm，碳管長度超過10 mm。將MWCNT浸泡或微波輻射於三種金屬奈米粒子前驅溶液(白金、金、鉀)，得到參雜白金(Pt/CNTs)、金奈米粒子(Au/CNTs)或鉀離子(K-CNTs)的多層奈米碳管，並將四種欲量測的樣品，商用奈米碳管(C-CNTs)、參雜白金奈米粒子的奈米碳管(Pt/CNTs)、參雜金奈米粒子的奈米碳管(Au/CNTs)、參雜鉀離子的奈米碳管(K-CNTs)分別經過BET量測後，其氫氣吸脫附量測結果為商用奈米碳管(C-CNTs)是0.0876 wt%、Pt/CNTs是0.0225 wt%、Au/CNTs是0.0604 wt%、K-CNTs是0.0908 wt%，而參雜鉀離子的奈米碳管儲氫效率較好，將與自製的奈米碳管作比較。
在自製奈米碳管實驗中，0.3μm粒徑大小的氧化鋁薄膜加上3克硝酸鐵溶液催化劑的基板所生長出來的自製奈米碳管較好，經過純化步驟過後，碳管直徑分布為50-100 nm，碳管長度超過10 mm，並利用浸泡將鉀金屬離子參雜至奈米碳管中。經過BET量測後，其氫氣吸脫附量測結果為：自製奈米碳管(S-CNTs)是0.0885 wt%、摻雜鉀離子之奈米碳管(SK-CNTs)是0.1199 wt%。
最後我們將商用及自製的奈米碳管去做儲氫效率的比較，氫氣吸脫附量測儲氫量的結果為商用奈米碳管原材的儲氫量為0.0876 wt%，但經過摻雜鉀離子之奈米碳管其儲氫量可提昇至0.0908 wt%；而自製奈米碳管的儲氫量為0.0885 wt% 但摻雜鉀離子之奈米碳管其儲氫量為0.1199 wt%，原因為自製奈米碳管其本身管狀結構比商用奈米碳管缺陷較多。
以上分析皆使用SEM來觀察奈米碳管的型態，Raman光譜來鑑定奈米碳管的結構，TEM來觀察奈米碳管的微結構，BET來量測奈米碳管的氫氣吸脫附量，並且探討市售奈米碳管以及自製奈米碳管的氣體吸附現象。

關鍵字

奈米碳管 ； 儲氫

並列摘要

In this study, multiwall carbon nanotubes were synthesized using low pressure chemical vapor deposition (LPCVD). The growth of carbon nanotubes on Si wafer substrates was explored by using varied amount of ferric nitrate solutions and different particle sized Al2O3 (1μm, 0.3μm, 0.1μm) powders as the catalytic agents.
Commercial carbon nanotubes (NCT tubes, Japan) as well as the as-synthesized carbon nanotubes were examined for their capability in hydrogen storage. The specification of commercial CNT was more than 99.5% of multi-walled carbon nanotube (MWCNT), 50-100 nm in diameter, and > 10 mm in length. Additives such as Pt nanoparticles, and Au nanoparticles, and dopants such as K were introduced to the studied carbon nanotubes in order to investigate their influences on hydrogen adsorption. The adsorption of hydrogen for the commercial carbon nanotubes (C-CNTs) was 0.0876 wt%. For Pt/CNTs, the H2 adsorption was 0.0225 wt%, the Au/CNTs 0.0604 wt%, and the K-CNTs 0.0908 wt%. The potassium ion-doped CNTs exhibited better hydrogen storage efficiency than others cases in this study. Hydrogen adsorption for as-synthesized carbon nanotubes (S-CNTs) is 0.0885 wt%, and the dopant of potassium ions could enhance the value up to 0.1199 wt% (SK-CNTs.) It was also confirmed that the higher defects in as-synthesized CNTs than those of commercial CNTs was the reason of their higher H2 adsorption capability. Raman spectroscopy, SEM, XRD, and TEM were employed to characterize all CNT materials in this study.

並列關鍵字

Hydrogen storage ； Carbon nanotubes

參考文獻

.徐逸明, “化學氣相沉積法及電漿輔助化學氣相沉積法於低溫合成奈米碳管之研究”, 國立成功大學化學工程研究所博士論文(2001)

.南台科技大學機械工程系 “微奈米技術第八章奈米碳管”

. L.Schlapbach et al., “Hydrogen-storage materials for mobile applications”, Nature 414, 353-358(2001).

. H. W. Kroto et al., “C60: Buckminsterfullerene”, Nature, 318, 162-163.(1985)

. S. Iijima et al., “Helical microtubules of graphitic carbon”, Nature(London), 354, 56~58 (1991)