单壁碳纳米管储氢的第一原理分子动力学模拟

Theoretical study of hydrogen adsorption in single-walled carbon nanotubes by first principles molecular dynamics method

本文用第一性原理平面波赝势方法模拟研究了手性单壁碳纳米管与氢分子的相互作用,考察了碳纳米管直径对储氢性能的影响.对单壁碳纳米管储氢的模拟结果表明:(1)物理吸附时,H_2可以吸附在空腔内,也可以吸附在管与管之间的空隙中,纳米管内部的氢吸附力均高于管外,而"完好无损"的H_2分子不能够穿过管壁而进入管内.(2)化学吸附时,碳纳米管对氢的吸附首先出现在管的边缘附近,碳纳米管局部会发生形变,SWCNTs的张力会随C—H键的增加而增大,系统不稳定.(3)随着直径的增加,纳米管内、外的氢吸附力差异减小.

Adsorption of hydrogen molecules in finite was presented using the first-principles plane-wave method. The hydrogen storages of different diameter hydrogen storage in SWCNTs show that： （1） When chiral single-walled carbon nanotubes （SWCNTs） pseudopotential molecular dynamics simulations nanotubes were studied. The simulation results of the physisorption happens, the H2 can adsorb in both the cavity of tube and the crevice between tubes. The hydrogen adsorption energy of SWCNTs in- ner is all higher than that outside of the tube, but the intact H2 molecules canrt go through the tube wall and enter tube inner. （2） When the chemisorption happens, the hydrogen adsorption first appears at the edge of SWCNTs. C atoms bonded with H atoms result in the structural deformation in parts of tube wall and tension of SWCNTs would aggrandize with the increment of the C--H bonds, so the system is unsteady. （3） Along with the increment of the diameter, the difference of hydrogen adsorption capabili- ty between the inside and outside of each SWCNT drops off.