Abstract As an adsorbent, carbon nanotubes integrate the advantages of activated carbon with a robust sp2 carbon framework and a defined pore structure. Due to the presence of multiple adsorption sites, vertically aligned carbon nanotubes (VACNTs) exhibit excellent adsorption characteristics at high pressures (∼30 bar). However, it is known that a large fraction of the as-synthesized VACNTs are closed and are inaccessible for the adsorptive. In the present study, we employ a high temperature CO2 treatment process to open the VACNTs under controlled conditions without altering their alignment. Opening of the CNTs is confirmed by TEM and N2 adsorption measurements and subsequently the surface area of the opened VACNTs increases by 60%. Consequently, a so far unreported adsorption step, corresponding to adsorption in the interior of the CNTs is observed in the N2 adsorption isotherm. High pressure adsorption studies on these opened VACNTs revealed a dramatic increase of more than 140% in CO2 adsorption compared to as-prepared VACNTs, which is almost double that of zeolite 13X and is at par with certain metal-organic frameworks.

中文翻译：

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垂直排列的碳纳米管中前所未有的 CO 2 吸收

摘要 作为一种吸附剂，碳纳米管结合了活性炭的优点、坚固的 sp2 碳骨架和明确的孔结构。由于存在多个吸附位点，垂直排列的碳纳米管（VACNT）在高压（~30 bar）下表现出优异的吸附特性。然而，众所周知，大部分合成的 VACNT 是封闭的，吸附剂无法进入。在本研究中，我们采用高温 CO2 处理工艺在受控条件下打开 VACNT，而不会改变它们的排列。通过 TEM 和 N2 吸附测量证实了 CNT 的打开，随后打开的 VACNT 的表面积增加了 60%。因此，迄今为止尚未报道的吸附步骤，在 N2 吸附等温线中观察到对应于 CNT 内部的吸附。对这些打开的 VACNT 进行的高压吸附研究表明，与制备的 VACNT 相比，CO2 吸附量显着增加了 140% 以上，几乎是沸石 13X 的两倍，并且与某些金属有机骨架相当。