We have used molecular dynamics simulations to investigate interaction of H2 molecules on the exterior surfaces of carbon nanotubes (CNTs): single and bundle types. At 80 K and 10 MPa, it is found that charge transfer occurs from a low curvature region to a high curvature region of the deformed CNT bundle, which develops charge polarization only on the deformed structure. The long-range electrostatic interactions of polarized charges on the deformed CNT bundle with hydrogen molecules are observed to induce a high local-ordering of H2 gas that results in hydrogen liquefaction. Our predicted heat of hydrogen liquefaction on the CNT bundle is 97.6 kcal kg^-1. On the other hand, hydrogen liquefaction is not observed in the CNT of a single type. This is because charge polarization is not developed on the single CNT as it is symmetrically deformed under the same pressure. Consequently, the hydrogen storage capacity on the CNT bundle is much higher due to liquefaction than that on the single CNT. Additionally, our results indicate that it would also be possible to liquefy H2 gas on a more strongly polarized CNT bundle at temperatures higher than 80 K.
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机译:我们已经使用分子动力学模拟研究了碳纳米管(CNT)外表面上的H2分子之间的相互作用:单个类型和束类型。发现在80 K和10 MPa下,电荷从变形的CNT束的低曲率区域向高曲率区域发生转移,这仅在变形的结构上产生电荷极化。观察到在变形的CNT束上极化电荷与氢分子的远距离静电相互作用会引起H2气体的局部高序化,从而导致氢液化。我们预测的CNT束上的氢液化热为97.6 kcal kg ^ -1。另一方面,在单一类型的CNT中未观察到氢液化。这是因为,由于在相同的压力下对称地变形,所以在单个CNT上不产生电荷极化。因此,由于液化,CNT束上的储氢能力比单个CNT上的储氢能力高得多。此外,我们的结果表明,在高于80 K的温度下,也可以将H2气液化到更强极化的CNT束上。
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