Quantum nature of adsorbed hydrogen on single-wall carbon nanohorns
Quantum nature of adsorbed hydrogen on single-wall carbon nanohorns
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DOI：
10.1080/08927020412331337032
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发表时间：
2005-05
影响因子：
2.1
通讯作者：
H. Tanaka;J. Fan;H. Kanoh;M. Yudasaka;S. Iijima;K. Kaneko
中科院分区：
文献类型：
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作者：
H. Tanaka;J. Fan;H. Kanoh;M. Yudasaka;S. Iijima;K. Kaneko
我们已经测量了N2在单壁碳纳米角（SWNHs）上的吸附等温线在77 - 92 K的温度范围内，并确定了等量吸附热，q st。SWNHs的吸附测量也已完成为H2在20 K，和H2和D2在77 K，分别。我们对单壁碳纳米管（SWNT）模型的N2、H2和D2进行了巨正则蒙特卡罗（GCMC）模拟，并与实验数据进行了比较。模拟N2吸附等温线的单壁碳纳米管束模型是在相当好的协议与实验等温线的SWNH组件在很宽的压力范围内，在77 K，然而，模拟Q ST值的单壁碳纳米管束表明，SWNH颗粒不完全安排在SWNH组件。在20 K时模拟的孤立单壁碳纳米管模型内的经典H2的内面等温线表明，由于大的量子效应，在SWNH颗粒的内部空间中的吸附H2的密度比经典H2的密度小得多。在模拟77 K时H2和D2在模型单壁碳纳米管束上的吸附等温线时，采用基于Feynman-Hibbs（FH）有效势的GCMC模拟，将量子效应引入经典Lennard-Jones（LJ）势产生的统计特性中.我们发现，从FH-GCMC模拟的单壁碳纳米管束上的H2到D2的吸附比小于0.91，这取决于吸附压力;这是因为即使在77 K下，由于H2分子的宽量子扩展，单壁碳纳米管束对H2的势场也相对弱于D2。
We have measured N2 adsorption isotherms on single-wall carbon nanohorns (SWNHs) over the temperature range of 77–92 K, and isosteric heat of adsorption, q st, were determined. Adsorption measurements for SWNHs have been also done for for H2 at 20 K, and for H2 and D2 at 77 K, respectively. We have performed grand canonical Monte Carlo (GCMC) simulations of N2, H2, and D2 for single-wall carbon nanotube (SWNT) models to compare with the experimental data. Simulated N2 adsorption isotherm on a SWNT bundle model is in reasonably good agreement with the experimental isotherm on the SWNH assembly over a wide range of pressures at 77 K; however, simulated q st-values for the SWNT bundle suggest that the SWNH particles are incompletely arranged in the SWNH assembly. Simulated endohedral isotherm of classical H2 inside an isolated SWNT model at 20 K showed that a density of adsorbed H2 in the internal space of the SWNH particle is quite smaller than that of classical H2 because of large quantum effects. In simulating H2 and D2 adsorption isotherms on the model SWNT bundle at 77 K, GCMC simulations based on the Feynman-Hibbs (FH) effective potential were applied to introduce quantum effects to the statistical properties generated by the classical Lennard-Jones (LJ) potential. We found that an adsorption ratio of H2 to D2 on the SWNT bundle from the FH-GCMC simulations is less than 0.91 depending on adsorption pressure; this is because the potential field of the SWNT bundle for H2 is relatively weaker than that for D2 even at 77 K, due to the wide quantum spreading of a H2 molecule.