ABSTRACT
The development of large-scale, high-purity production methods for carbon nanotubes (CNTs) is highly desirable for further increasing the practical applications of these fascinating materials. In addition to the previously known laser furnace [1] and arc discharge techniques [2], catalytic chemical vapor deposition (CCVD) methods [3-10] have been widely pursued as a potential low-cost, large-scale production method. In earlier versions of this technique, such as the high-pressure carbon monoxide method [7], §oating catalysts were used during the CVD process. However, more recently, a high-purity technique for production of vertically aligned singlewalled CNTs on a quartz substrate has been developed using a supported catalyst [8], which was followed by a later režnement by the addition of water, resulting in very long (millimeter-thick) nanotube forests [9], and later termed “super growth” [11]. Koziol et al. [12] have reported mechanical property data from high-performance CNT žbers, in which the addition of sulfur was critical for promoting the formation
6.1 Introduction ....................................................................................................77 6.2 Computational Methodology ..........................................................................80 6.3 Results ............................................................................................................. 82
6.3.1 Freestanding Mon Clusters ................................................................. 82 6.3.2 Freestanding Mo-X Clusters ..............................................................85 6.3.3 Endohedral Mon@C180 ........................................................................87 6.3.4 Endohedral Mo(52 – x)Sx@C180 .............................................................. 91
6.4 Conclusions .....................................................................................................92 Acknowledgments ....................................................................................................93 References ................................................................................................................93
