三种缺陷碳纳米管储氢性能分子动力学模拟研究

Research on molecular dynamics simulations on hydrogen storage in carbon nanotubes with topological defects

采用分子动力学(M D)方法对3种含有缺陷的椅式(5,5)、椅式(6,6)和齿式(10,0)碳纳米管储氢能力进行了模拟研究,考查了缺陷大小、缺陷位置、碳纳米管直径和螺旋性以及温度对碳纳米管储氢性能的影响.模拟结果表明:碳纳米管在80 K时的储氢能力明显高于298K时的储氢能力;在相同条件下,直径较大的碳纳米管储氢性能优于直径较小的;当碳纳米管上的缺陷孔较小时,碳纳米管在室温下即可达到较高的储氢量,且缺陷位于碳纳米管端部时的储氢量大于缺陷位于管壁时的储氢量,而碳纳米管的螺旋性对储氢量影响较小;当缺陷孔的尺寸变大时,碳纳米管的储氢量明显下降,与此同时,碳纳米管的螺旋性对碳纳米管储氢量的影响趋于明显,而缺陷所在位置对储氢量的影响则相应减弱.

Molecular dynamics （MD） simulations are carried out to investigate the hydrogen storage in three carbon nanotubes （CNTs） with defects. The effects of the temperature, helicity and defect position and size on the hydrogen storage capability of CNTs have been investigated. The results show that the hydrogen storage capability in CNTs at 80 K is much higher than that at 298 K, and CNTs with larger diameter are favorable to hydrogen storage. It is also found that when the defect is small, high density of hydrogen molecules can be confined into CNTs even at room temperature and more hydrogen molecules can be stored into CNTs when the defect is on the top than on the sidewall, while the chirality effect is not obvious. However, as the defect size becomes bigger, the maximum hydrogen confined into CNT decreases and the effect of the defect position on the hydrogen storage becomes weak, and in the mean time the chirality effect becomes more obvious.