Towards chirality-pure carbon nanotubes

Abstract

Current as-grown single-walled carbon nanotubes vary in diameter and chirality, which results in variations in their electronic and optical properties. Two approaches have been intensively studied to obtain chirality-pure nanotube structures and thus uniform properties for advanced applications. The first approach involves the post-synthesis separation according to the nanotubes' chiral vectors (n, m), and the second one involves direct synthes of carbon nanotubes with the same (n, m). This paper reviews the efforts along these two directions, with emphasis on the most recent progress of post-synthesis separation and the perspectives of controllable synthesis.

The role of sodium dodecyl sulfate concentration in the separation of carbon nanotubes using gel chromatography

“…Consequently, the demand for uniformity in nanotube distributions has lead to post-synthesis sorting of CNTs being approached in a variety of different ways, with varied levels of success [1,2]. Recently, polysaccharide gel chromatography has emerged as an effective technique for obtaining metalsemiconductor separation, as well as for producing solutions highly enriched in individual nanotube species [3,4].…”

Carbon Fibers and Their Composites

“…CNTs are inert in pristine state and tend to bundle together because of the strong van der Waals interactions, making them difficult to disperse uniformly in aqueous or any organic solvents. Some special methods involving oxidation and grafting with different functionalities [61][62][63][64][65] have been used to overcome this issue; however, these methods normally destroy the intrinsic structure and properties of the CNTs. Thus, these methods are unfavorable for fiber spinning.…”

Combinatorial approach for the synthesis of precursors for chirality-controlled synthesis of SWCNTs

“…4c. In the same manner, the combinatorial synthesis utilizing ketones K1 and K3 (precursor molecules are not shown) will result in the formation of precursors for 22 chiralities, namely-(6,6), (7,5), (8,4), (9,3), (8,8), (9,7), (10,6), (11,5), (12,4), (10,10), (11,9), (12,8), (13,7), (14,6), (15,5), (12,12), (13,11), (14,10), (15,9), (16,8), (17,7), and (18,6). Correspondingly, the combination of K3 and K2a will give a mixture of 22 precursors for (9,0), (9,1), (9,2), (9,3), (12,0), (12,1), …”

“…The corresponding higher homologues, i.e., the tetramer, pentamer, and hexamer, represent highly attractive precursors for large diameter SWCNTs. Thus, for example, the condensation of rather simple cyclic ketone K1 has resulted in the simultaneous formation of precursors for four different chiralities, namely (6,6), (8,8), (10,10), and (12,12) (Fig. 2).…”