钙覆盖的富勒烯作为高存储容量的储氢材料

Calcium Coated Fullerenes for High-Capacity Hydrogen Storage

文章从理论上研究了轻碱土金属覆盖的富勒烯作为储氢介质的可行性.基于第一性原理密度泛函理论计算,文章作者发现Ca和Sr在C60表面的吸附很强,并且倾向于形成单层覆盖.这种强吸附归因于这类金属元素未占据的d轨道参与的一种独特的电荷转移机制.电荷的重新分布在金属覆盖的富勒烯表面附近产生强电场,使得金属-富勒烯复合物成为理想的氢分子吸附中心.Ca32C60复合物的理论储氢质量百分比达到8.4wt%,因此,在富勒烯+金属体系的储氢介质研究中,Ca优于目前提出的所有覆盖富勒烯的金属元素.

We explore theoretically the feasibility of functionalizing carbon nanostruetures for hydrogen storage, focusing on the coating of C60 fullerenes with light alkaline-earth metals. Our first-principles density functional theory studies show that both Ca and Sr can bind strongly to the C60 surface, and highly prefer monolayer coating. The strong binding is attributed to an intriguing charge transfer mechanism involving the empty d levels of the metal elements. The charge redistribution, in turn, gives rise to electric fields surrounding the coated fullerenes, which can now function as ideal attractors upon molecular hydrogen adsorption. With a hydrogen uptake of 〉 8.4 wt% on Ca32C60, Ca is superior to all the recently suggested metals for metal coated fullerenes in hydrogen storage.