Chemisorption of molecular hydrogen on carbon nanotubes: A route to effective hydrogen storage?
Chemisorption of molecular hydrogen on carbon nanotubes: A route to effective hydrogen storage?
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DOI：
10.1021/jp802104n
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发表时间：
2008-08-14
影响因子：
3.7
通讯作者：
Gale, Julian D.
中科院分区：
文献类型：
--
作者：
Bilic, Ante;Gale, Julian D.
采用第一性原理密度泛函理论（DFT）研究了氢分子在小直径扶手椅型碳纳米管上的化学吸附。氢的吸附进行了检查，在一系列的覆盖率，从低到全单层覆盖。研究了几种氢化途径，并确定了那些可能导致完全饱和纳米管的能量有利的稳定结构的途径。对于这些途径，计算表明，除了在开始时，氢的添加是放热的，并且随着覆盖度的增加也变得越来越有利。足够小直径的碳纳米管被证明有能力通过化学吸附有效地储存整个单层的氢。此外，动力学障碍的解离化学吸附的H-2和系统的热平衡被认为是。这些被发现是相当大的admolecules上的一个otherwise-clean纳米管，但大幅下降附近的预吸附的氢，也就是说，吸附的氢作为一个自动催化剂进一步氢化。在这些发现的基础上，氢与碳纳米管的化学反应预计将变得越来越放热，并且在更高的覆盖率下进行得更快。
The energetics of the chemisorption of molecular hydrogen on small-diameter armchair carbon nanotubes has been investigated using first-principles density functional theory (DFT). The adsorption of hydrogen was examined at a range of coverages, from low to full monolayer coverage. Several pathways for hydrogenation were investigated, and those that could lead to energetically favorable, stable structures of fully saturated nanotubes were identified. For these routes, the calculations indicate that the addition of hydrogen, apart from at the very onset, is exothermic and also becomes increasingly more favorable with increasing degree of coverage. Carbon nanotubes of sufficiently small diameter are shown to have the capacity to store a full monolayer of hydrogen effectively via chemisorption. In addition, kinetic barriers for the dissociative chemisorption of H-2 and thermal equilibration of the system were considered. These were found to be quite large for admolecules on an otherwise-clean nanotube, but to drop substantially in the vicinity of preadsorbed hydrogen; that is, the adsorbed hydrogen acts as an autocatalyst for further hydrogenation. On the basis of these findings, the chemical reaction of hydrogen with carbon nanotubes is expected to become increasingly exothermic and also to proceed more rapidly at higher coverages.