Pretreatment Control of Carbon Nanotube Array Growth for Gas Separation: Alignment and Growth Studied Using Microscopy and Small-Angle X-ray Scattering

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• 作者：Xiaoshuang Yang ; Lixiang Yuan ; Vanessa K. Peterson ; Andrew I. Minett ; Ming Zhao ; Nigel Kirby ; Stephen Mudie ; Andrew T. Harris
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2013
• 出版时间：April 24, 2013
• 年：2013
• 卷：5
• 期：8
• 页码：3063-3070
• 全文大小：506K
• 年卷期：v.5,no.8(April 24, 2013)
• ISSN：1944-8252

文摘

Aligned multiwalled carbon nanotube (CNT) arrays were prepared using chemical vapor deposition of C₂H₄ on Fe catalyst at 750 掳C. CNT array height and alignment depends strongly on the duration of H₂ pretreatment, with optimal height and alignment achieved using 10鈥?5 min pretreatment. Small-angle X-ray scattering (SAXS) was used to quantify the alignment, distribution, and size of the CNTs in arrays produced from varying pretreatment times and the results correlated with microscopy measurements. SAXS analysis revealed that the higher section of the CNT arrays exhibited better alignment than the lower section. Combining these insights with transmission electron microscopy measurements of the CNT defects within each array enable a mechanism for the CNT growth to be proposed, where the loss of alignment arises from deformation of the CNTs during their growth. Gas permeation test across densified CNT arrays indicated that the alignment of the CNT array plays an important role in the gas transport, and that the gas diffusion across the well-aligned CNT arrays was enhanced by a factor of 45, which is much more than that across the poorly aligned CNT arrays, with an enhancement factor of 8.

Keywords:

catalysts; alignment control; growth mechanism; gas transport