First-principles study of hydrogen storage on Li12C60.
First-principles study of hydrogen storage on Li12C60.
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DOI：
10.1021/ja058330c
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发表时间：
2006-07
影响因子：
15
通讯作者：
Qiang Sun;P. Jena;Qian Wang;M. Márquez
中科院分区：
文献类型：
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作者：
Qiang Sun;P. Jena;Qian Wang;M. Márquez
能够以高重量（9 wt %）和高体积密度（70 g/L）储存氢的固态材料对于新型氢经济的成功至关重要。此外，理想的储氢系统应该能够在环境热力学条件下运行，并表现出快速的氢吸附动力学。没有已知的材料满足所有这些要求。虽然最近的理论研究表明过渡金属包覆的碳富勒烯有一定的前景，但后来的研究表明，这些金属原子更倾向于聚集在富勒烯表面，从而大大减少了储存氢的重量百分比。利用密度泛函理论，我们发现锂包覆的富勒烯不受这种限制。特别是，我们发现一个孤立的Li(12)C（60）簇，其中Li原子被封顶在富勒烯的五边形表面上，不仅非常稳定，而且可以以分子形式存储多达120个氢原子，结合能为0.075 eV/H(2)。此外，当允许Li(12)C（60）簇相互作用时，它们的结构完整性得以保持。二聚体的最低能量结构是一个富勒烯的五元环上的Li原子与另一个富勒烯的六元环结合。讨论了氢与Li原子的结合以及由Li(12)C（60）组成的储氢材料的潜力。
Solid state materials capable of storing hydrogen with high gravimetric (9 wt %) and volumetric density (70 g/L) are critical for the success of a new hydrogen economy. In addition, an ideal storage system should be able to operate under ambient thermodynamic conditions and exhibit fast hydrogen sorption kinetics. No materials are known that meet all these requirements. While recent theoretical efforts showed some promise for transition-metal-coated carbon fullerenes, later studies demonstrated that these metal atoms prefer to cluster on the fullerene surface, thus reducing greatly the weight percentage of stored hydrogen. Using density functional theory we show that Li-coated fullerenes do not suffer from this constraint. In particular, we find that an isolated Li(12)C(60) cluster where Li atoms are capped onto the pentagonal faces of the fullerene not only is very stable but also can store up to 120 hydrogen atoms in molecular form with a binding energy of 0.075 eV/H(2). In addition, the structural integrity of Li(12)C(60) clusters is maintained when they are allowed to interact with each other. The lowest energy structure of the dimer is one where the Li atom capped on the five-member ring of one fullerene binds to the six-member ring of the other. The binding of hydrogen to the linking Li atom and the potential of materials composed of Li(12)C(60) building blocks for hydrogen storage are discussed.