The dynamics of H₂ and N₂ sorption in carbon nanotubes

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• 作者：&Ouml ; tv&ouml ; s ; Zs. ; Onyestyá ; k ; Gy. ; Valyon ; J. ; Kiricsi ; I. ; Kó ; nya ; Z. ; Rees ; L.V.C.
• 关键词：61.46 ; 82.20 R ; 68.45 D ; 66.30 ; Carbon nanotubes ; Rate spectroscopy ; Adsorption ; Diffusion
• 刊名：Applied Surface Science
• 出版年：2004
• 期刊代码：6_01694332
• 类别：ms
• 出版时间：November 15, 2004
• 卷：238
• 期：1-4
• 页码：73-76
• 文件大小：115 K

摘要

Single-walled and multi-walled carbon nanotubes (SWNT and MWNT) were prepared by catalytic decomposition of methane and acetylene, respectively. The resulting catalyst/carbon composites were subjected to chemical treatments to obtain samples which were enriched in nanotubes. Isotherms and frequency response (FR) spectra of N₂ and H₂ were recorded at 195 and 77K, respectively, in the 1–800Pa pressure range. The adsorption isotherms for N₂ were found to obey Henry’s law, while the isotherms of H₂ adsorption indicated some energetic heterogeneity of the sorption sites. Stronger adatom–substrate interaction was detected for those samples which had been subjected to oxidative treatment. The FR measurements showed that treatment of MWNT in KMnO₄ solution changed the rate-controlling mechanism of mass transport from one of sorption to one of diffusion. Results substantiated that the surface functional groups, generated by the oxidative treatment, have significant influence on both the equilibrium and the dynamic N₂ and H₂ sorption properties of the carbon nanotubes.