二氧化钛纳米管储氢能力的分子动力学研究

Study on capacity of hydrogen storage of TiO_2 nanotubes with molecular dynamics simulation

二氧化钛纳米管是一种有前景的储氢材料,因此,在本文中通过卷曲锐钛矿单分子层,获得锯齿型(Zig-zag)和手性型(Chiral)二氧化钛纳米管结构。并采用分子动力学方法(Molecular dynamics)研究了氢分子分别在锯齿型和手性型二氧化钛纳米管和碳纳米管中的分布情况,并计算其储氢能力。结果表明,与碳纳米管一样,锯齿型和手性型二氧化钛纳米管存在管间储氢和管内储氢情况,并且氢分子在管间和管内的分布与二氧化钛纳米管内、外两侧的氧原子相关。Lennard-Jones势能模型表明:氢分子向纳米管内部和管间隙处的低能处聚集,形成氢分子环结构。储氢量计算结果表明,虽然锯齿型和手性型二氧化钛纳米管储存的氢分子数目较多,但由于系统重量较大,储氢量较低,低于美国能源部6%的商业标准,不能满足实际需要,而碳纳米管储氢量接近这一标准。

TiO2 nanotube is a potential material for hydrogen storage. Therefore, in this study, the structures of prototypical single- walled TiO2 nanotubes, namely zigzag （ 12,0） and chiral （0,3）, were simulated by rolling molecular monolayer of anatase crystal into a cylinder. Furthermore, the dispersed status of hydrogen molecules in TiOz nanotubes and ihe capacity of hgdrogen storage were dis-cussed with molecular dynamics simulation. The results showed that both of TiO2 nanotubes have hydrogen tings at the inside and the outside,whieh connected with the oxygen atoms of nanotubes. Lennard-Jones model provided that hydrogen molecules gathered in the place with lower energy. Meanwhile, TiO2 nanotubes have lower capacities of hydrogen storage, although both of them havemore hydrogen molecules in their systems. However, C nanotube has better capacity of hydrogen storage, which close to the criterion of 6% of department of energy of USA（DOE）.