Echt Olof, Kaiser Alexander, Zöttl Samuel, Mauracher Andreas, Denifl Stephan, Scheier Paul
Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Techniker Strasse 25, A-6020 Innsbruck (Austria).
Department of Physics, University of New Hampshire, Durham, NH 03824 (USA).
Chempluschem. 2013 Sep;78(9):910-920. doi: 10.1002/cplu.201300198. Epub 2013 Jul 31.
Physisorption on graphite, graphene, nanotubes, and other graphitic structures has been the subject of numerous studies, partly driven by interest in the nature of order in two-dimensional systems, their phase transitions, and the use of graphitic scaffolds for reversible storage of hydrogen at high volumetric density and low mass. In contrast, physisorption on individual fullerenes or small aggregates of fullerenes has remained largely unexplored, last but not least, because of technical challenges. A summary of recent progress in identifying specific adsorption sites on positively charged C , C , and their aggregates is given in this Minireview. Adsorption energies and storage capacities for helium, hydrogen, methane, oxygen, nitrogen, water, and ammonia are determined. Mass spectrometric data reveal the formation of a commensurate phase in which all hollow sites of C or C are occupied. This phase is identified for all nonpolar molecules, including oxygen, which does not form a commensurate phase on planar graphite. The polar molecules, on the other hand, do not wet fullerenes and they do not form this commensurate phase. A hierarchy of other distinct adsorption sites are identified for nonpolar molecules, namely, groove sites for fullerene dimers and beyond, and dimple sites for fullerene trimers and beyond. Furthermore, evidence is presented for the preferential adsorption of hydrogen and methane in registered sites on fullerene dimers. The interpretation of experimental data that merely count the number of preferred adsorption sites is aided by molecular dynamics simulations, which utilize interaction potentials derived from ab initio calculations to determine adsorption energies.
在石墨、石墨烯、纳米管及其他石墨结构上的物理吸附一直是众多研究的主题，部分原因是人们对二维系统中的有序本质、它们的相变以及利用石墨支架在高体积密度和低质量下可逆储存氢气感兴趣。相比之下，在单个富勒烯或富勒烯小聚集体上的物理吸附在很大程度上仍未得到探索，这尤其是因为技术挑战。本微型综述给出了在带正电的C 、C 及其聚集体上确定特定吸附位点的最新进展总结。确定了氦、氢、甲烷、氧气、氮气、水和氨的吸附能及储存容量。质谱数据揭示了一种共格相的形成，其中C 或C 的所有中空位点都被占据。对于所有非极性分子，包括在平面石墨上不形成共格相的氧气，都确定了这种相。另一方面，极性分子不会浸润富勒烯，也不会形成这种共格相。为非极性分子确定了其他不同吸附位点的层级结构，即富勒烯二聚体及更大聚集体的沟槽位点，以及富勒烯三聚体及更大聚集体的凹坑位点。此外，还给出了氢气和甲烷在富勒烯二聚体上的配位点优先吸附的证据。分子动力学模拟有助于解释仅计算优先吸附位点数目的实验数据，该模拟利用从头算计算得出的相互作用势来确定吸附能。
