利用碳原子链实现高容量储氢：末端的作用
Realization of high-capacity hydrogen storage using carbon atomic chains: the role of terminations
摘要：
采用第一性原理密度泛函理论计算了不同末端碳原子链的储氢容量。与H-封端链上的H2的物理吸附不同，我们表明，两个Li（Na）原子，每个封端的碳链的一端可以容纳10个H2分子，具有最佳的结合能，用于室温储存。Li 2 p态与H2 σ轨道的杂化有助于H2吸附。然而，H2分子对Na的结合机制仅来自带电Na原子与H2之间的极化相互作用。此外，由于Li 2s 2 p（Na 3s）和C 2 p态之间的电荷转移，额外的H2分子可以结合到链末端的碳原子上。重要的是，这些孤立的金属封端的链的二聚化不影响氢结合能显着。此外，单链可以通过终止在C60簇上而有效地稳定。在Li涂覆的C60-Cn-C60（n = 5，8）上的氢吸收> 10重量%的情况下，Li 12 C60-Cn-Li 12 C60络合物可以充当比（Li 12 C60）2二聚体更好的聚合物结构单元，而不减少每个Li吸附的H2分子的数量。这些发现为基于末端sp碳链的团簇组装储能材料的设计提供了一条新的途径。
英文摘要：
The capacity of carbon atomic chains with different terminations for hydrogen storage is studied using first-principles density functional theory calculations. Unlike the physisorption of H2 on the H-terminated chain, we show that two Li (Na) atoms each capping one end of the carbon chain can hold ten H2 molecules with optimal binding energies for room temperature storage. The hybridization of the Li 2p states with the H2 sigma orbitals contributes to the H2 adsorption. However, the binding mechanism of the H2 molecules on Na arises only from the polarization interaction between the charged Na atom and the H2. Moreover, additional H2 molecules can be bound to the carbon atoms at the chain ends due to the charge transfer between Li 2s2p (Na 3s) and C 2p states. Importantly, dimerization of these isolated metal-capped chains does not affect the hydrogen binding energy significantly. In addition, a single chain can be stabilized effectively by termination on the C60 clusters. With a hydrogen uptake of > 10 wt % on Li-coated C60-Cn-C60 (n = 5, 8), the Li12C60-Cn-Li12C60 complex, without reducing the number of adsorbed H2 molecules per Li, can serve as better building blocks of polymers than the (Li12C60)2 dimer. These findings suggest a new route to design cluster-assembled storage materials based on terminated sp carbon chains.
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