Experimental Information on the Adsorbed Phase of Water Formed in the Inner Pore of Single-Walled Carbon Nanotube Itself
Experimental Information on the Adsorbed Phase of Water Formed in the Inner Pore of Single-Walled Carbon Nanotube Itself
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DOI：
10.1021/acs.langmuir.5b04222
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发表时间：
2016-02-02
期刊：
影响因子：
3.9
通讯作者：
Kuroda, Yasushige
中科院分区：
文献类型：
--
作者：
Nishi, Masayasu;Ohkubo, Takahiro;Kuroda, Yasushige
迄今为止，还没有人根据实验程序成功获得单壁碳纳米管（SWCNT）本身圆柱形微孔内形成的气体或蒸气吸附相的性质的准确信息。在这项工作中，我们通过在不改变表面状态的情况下打开由封闭端SWCNT组成的孔，并应用独特的表征方法，成功地通过实验分析了限制在SWCNT本身内部孔中的吸附氮和水的性质；即使在将开放式结构引入封闭式结构的处理之后，表面官能团和束结构的数量和性质也是相同的。结果，通过分析在 77 K 下测量的开口端 SWCNT 和封闭端 SWCNT 上的吸附量之间各自的氮吸附等温线差异，可以获得两种类型样品的平均孔径以及特征吸附行为。评估的孔径与拉曼数据估计的结果非常吻合。这些结果有力地支持了我们可以通过应用本方法来分析仅在单壁碳纳米管内孔中形成的吸附相。此外，我们可以分析单壁碳纳米管圆柱形微孔内形成的水的吸附相，显示吸附水的密度随孔径的变化与本体水的值的差异；对于平均孔径为1.3和1.7 nm的SWCNT，吸附水的密度分别为0.62和0.71 g·mL(-1)，这与其他研究人员报道的理论计算得到的结果一致。所提出的分析方法使得能够更精确、正确地识别SWCNT圆柱形微孔内形成的吸附水的聚焦状态。所提出的方法将阐明与 SWCNT 中各种吸附气体的详细性质、孔内形成的吸附物质在各种现象中的详细作用以及基于所获得的知识设计有用材料相关的讨论。
Thus far, nobody has successfully obtained the accurate information on the properties of the adsorbed phases of gases or vapors formed inside a cylindrical micropore of single-walled carbon nanotube (SWCNT) itself based on the experimental procedure. In this work, we succeeded in analyzing experimentally the properties of adsorbed nitrogen and water confined in the inner pore of SWCNT itself by opening the pore composed of close-ended SWCNT without any changes in the surface state and also by applying the unique method for characterization; both the amounts, as well as properties, of surface functional groups and the bundle structure are the same even after the treatments for introducing an open-ended structure to a close-ended one. As a result, the average pore sizes, as well as characteristic adsorption behavior, on the two types of sample were available from the analysis of respective difference adsorption isotherms of nitrogen measured at 77 K between the adsorbed amounts on the open-ended SWCNT and that on the close-ended one. The evaluated pore sizes well coincide with the results estimated by Raman data. These results strongly support that we could analyze the adsorbed phases formed only in the inner pore of SWCNTs by applying the present method. Furthermore, we could analyze the adsorbed phase of water formed inside the cylindrical micropore of SWCNTs, showing the difference in the densities of adsorbed water depending on the pore sizes from the value of bulk water; the densities of the adsorbed water were evaluated to be 0.62 and 0.71 g mL(-1) for SWCNTs having average pore sizes of 1.3 and 1.7 nm, respectively, which were in harmony with those obtained by the theoretical calculations reported by other researchers. The proposed analysis method makes it possible to recognize the focused states of the adsorbed water formed inside the cylindrical micropore of SWCNT more precisely and correctly. The method proposed will shed light on the discussion related to the detailed nature of various adsorbed gases into SWCNT, to the detailed role of adsorbed species formed inside pore in various phenomena, and to the designing the useful materials based on the gained knowledge.