碱土金属Mg外掺杂硼笼B40Mg6的储氢性能

对外掺杂碱土金属Mg的B₄₀硼笼的储氢性能进行了密度泛函理论研究. 结果表明, B₄₀笼含有2个六元环与4个七元环. 多个Mg原子对B₄₀笼进行外掺杂时不会发生成簇现象, 有利于进一步储氢. Mg原子外掺杂的B₄₀笼对H₂分子的平均吸附能介于物理吸附与化学吸附之间(0.1~0.8 eV). 体系的储氢密度达到7.60%(质量分数). 储氢结构能在常温常压下释放H₂分子, 因此, Mg原子外掺杂的B₄₀笼比Mg合金具有更好的储氢性能.

Hydrogen Storage Capacity of the Alkaline Earth Metal Mg Exohedral Doped Boron Cage B40Mg6?

The density functional theory(DFT) was used to study the hydrogen storage capacity of alkaline earth metal Mg exohedral doped B₄₀ cage structure. There are two B₆ hexagon rings and four B₇ heptagon rings in the B₄₀ cage. The clustering of the Mg atoms on the surface of the B₄₀ cage can be effectively avoided, which should be benefit for the further hydrogen storage. The average adsorption energy of H₂ molecules is intermediate between physical adsorption and chemisorption. The hydrogen gravimetric density of B₄₀Mg₆ is 7.60%(mass fraction), which far exceed the target of 5.5%(mass fraction) by the year 2017 specified by the US Department of Energy. The hydrogen adsorbed structure tends to desorb hydrogen under the near-ambient conditions. Therefore, the Mg atom exohedral doped B₄₀ cage has better hydrogen storage capacity than Mg alloy. This research can provide a very important theoretical basis for the development of hydrogen storage materials.