High-Temperature Growth of Chirality-Enriched, Highly Crystalline Carbon Nanotubes for Efficient Single-Chirality Separation

There has been significant interest in producing single-walled carbon nanotubes (SWNTs) with specific chirality to ensure consistent and predictable performance. However, chirality-selective growth has traditionally required low reaction temperatures, causing SWNTs with low graphitization degrees. In this work, a magnesia supported cobalt catalyst (Co/MgO) is introduced for chemical vapor deposition growth of SWNTs with a narrow chirality distribution even at a high temperature of 900 degrees C, which promotes enhanced graphitization of SWNT walls. The achievement is attributed to the strong metal-support interactions that prevent catalyst particle sintering under harsh reaction conditions. The resulting SWNTs provide fundamental raw materials for high-efficiency single-chirality separation. Because of the relatively large chiral differences between the major species and their narrow chirality distribution, the study can readily isolate six distinct (n, m) SWNT types including (6, 5), (8, 3), (9, 2), (7, 5), (7, 6), and (8, 4), with purities exceeding 91% by gel chromatography. Compared with commercially HiPco- and CoMoCAT SG65i- SWNTs, the separation efficiency and yield are greatly improved. This work demonstrates the growth of high-quality SWNTs with a narrow chirality distribution, paving the way toward their efficient single-chirality separation.