Synthesis of fullerene encased single-walled carbon nanotube by means of electro-chemistry

采用电化学方法，在DMF中用高氯酸锂电解液从C60的甲苯溶液中对单壁碳纳米管中的富勒烯进行掺杂。对C&lt；60&gt；富勒烯施加约-0.5V的还原电压，以便将富勒烯分子掺杂到附着在铂电极两端的单壁碳纳米管垫上。结果表明，附着在正极上的SWNT垫完全包裹了C&lt；60&gt；分子。另一方面，负极上的单壁碳纳米管很少包裹富勒烯；富勒烯大部分在管的外面，锂附着在管的表面。这些事实表明，C&lt；60&gt；的阴离子由于静电力而接近正极，并被有效地包裹在单壁碳纳米管中。为了阐明C&lt；60&gt；分子从阵列结构到管状结构的聚合过程，利用拉曼散射光谱详细研究了在纳米管空间进行的C&lt；60&gt；分子的热聚合过程。结果，在主体管内形成了直径为0.7 nm的管子，并将管子的直径改为大直径，以使管壁间距与范德华距离相匹配。提出了一种基于(9，0)弯管成形的内管直径变换模型。本项目还进行了双壁碳纳米管的溴掺杂实验，发现电子可以从外管转移到溴分子中，但不能从内管转移到溴分子中。这一事实也得到了基于自我一致的紧密、约束模型计算的理论论证的支持，该计算是作为与宾夕法尼亚州立大学该小组的合作工作进行的。

By using the electro-chemistry method, doping of Fullerenes within the single-wall carbon nanotube (SWNT) was carried out from the toluene solution of C60 with electrolyte of lithium-perchiorate in DMF. Reduction voltage of ca. -0.5 V for C_<60> fullerene was applied in order to dope the fullerene molecules to SWNT mats, which were attached on the both ends of the Pt-plate electrodes. As results, SWNT mat attached on the positive electrode fully encases the C_<60> molecules. On the other hand, SWNT mat on the negative electrode rarely encases the fullerene ; most of the fullerenes were on the outside of the tube and Li was attached on the surface. These facts suggest that the anion of C_<60> was approached to the positive electrode due to electrostatic force and was efficiently encased within the SWNT. Thermal polymerization of C_<60> molecules, which is progressed in the nanotube space, was investigated detailedly by using Raman scattering spectroscopy in order to clarify the polymerization process from the array structure of C_<60> molecules to the tubular structure. As a result, 0.7 nm diameter tubes were formed inside the host tube and the diameter of the tube was changed to large diameters in order to match the inter-tube-wall separation with the van der Waals distance. We proposed a diameter transformation model for the inner tubes, which is based on forming the (9,0) zig-zag tube at first. Experiments of bromine doping to the double-wall carbon nanotubes were also carried out in the present program, and we found that the electrons can be transferred to the bromine molecules from the outer tubes, but they cannot be transferred from the inner tubes. This fact was also supported by the theoretical arguments based on the self-consistent tight, binding model calculation, which was carried out as the collaboration work with the group at Pennsylvania State University.