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Nanopore structure analysis of single wall carbon nanotube xerogels and cryogels
Adsorption ( IF 3.0 ) Pub Date : 2021-04-03 , DOI: 10.1007/s10450-021-00315-x
Yuito Kamijyou , Radovan Kukobat , Toshio Sakai , Katsumi Kaneko

We fabricated two types of single wall carbon nanotube (SWCNT) gels prepared by freeze-drying (cryogels) and air-drying (xerogels) from the dispersed SWCNT hydrogels. The comparative pore structure analysis using N2 adsorption at 77 K and H2O adsorption at 298 K was applied to these SWCNT gels. The N2 adsorption isotherms of both SWCNT gels have a steep initial uptake, low-pressure adsorption hysteresis and adsorption hysteresis above P/P0 = 0.9, indicating the presence of pore mouth structures in addition to micropores and mesopores. The mesoporosity of the SWCNT cryogels was about twice higher than that of the SWCNT xerogels, while their microporosities were similar. The H2O adsorption isotherms of both SWCNT gels differ from each other along the whole P/P0 range. The H2O adsorption isotherm of the SWCNT xerogels shows an explicit adsorption below P/P0 = 0.1 and marked low-pressure adsorption hysteresis; the pore mouth volume of the SWCNT xerogels from the initial uptake of H2O was nearly three times larger than that of the SWCNT cryogels. The H2O adsorption isotherms of our SWCNTs gels give similar micropore volumes, being by ≈ 40% larger than that of N2 adsorption isotherms. The excess micropore volume evaluated by H2O adsorption comes from the pore mouth structures in which N2 cannot access. This work demonstrates that H2O adsorption and N2 adsorption analysis are crucial for elucidation of the pore mouth structure.



中文翻译:

单壁碳纳米管干凝胶和冰凝胶的纳米孔结构分析

我们从分散的SWCNT水凝胶中制备了两种类型的单壁碳纳米管(SWCNT)凝胶,这些凝胶是通过冷冻干燥(冷冻凝胶)和风干(干凝胶)制备的。将这些在SWCNT凝胶上进行的孔结构比较分析(使用77 K的N 2吸附和298 K的H 2 O吸附)。两种SWCNT凝胶的N 2吸附等温线均具有陡峭的初始吸收,低压吸附滞后和高于P / P 0  = 0.9的吸附滞后,表明除微孔和中孔外还存在孔口结构。SWCNT凝胶的中孔性比SWCNT干凝胶的中孔性高大约两倍,而它们的微孔性却相似。H 2两种SWCNT凝胶的O吸附等温线在整个P / P 0范围内互不相同。SWCNT干凝胶的H 2 O吸附等温线在P / P 0  = 0.1以下显示出明显的吸附,并具有明显的低压吸附滞后。最初从H 2 O吸收而来的SWCNT干凝胶的孔口体积几乎是SWCNT凝胶的三倍。我们的SWCNTs凝胶的H 2 O吸附等温线具有相似的微孔体积,比N 2吸附等温线大约40%。通过H 2 O吸附评估的多余微孔体积来自其中N 2的孔口结构无法访问。这项工作表明H 2 O吸附和N 2吸附分析对于阐明孔口结构至关重要。

更新日期:2021-04-04
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