Chirality-Selective Coalescence of Carbon Nanotubes : Mechanism and Implications

Two carbon nanotubes with the same chiral indices (n,m) are shown to coalesce into a (2n,2m) nanotube, preserving the chiral angle. This process occurs efficiently at temperatures below 1000℃. The reaction efficiency shows a strong dependence on the chiral angle, suggesting a sequential mechanism involving C–C bond cleavage and recombination. Furthermore, the reaction is observed to proceed effectively even at 600℃, in the presence of trace oxygen. These findings establish routes for the structure-selective synthesis of large-diameter nanotubes and provide a versatile post-processing approach for modifying the structural and electronic properties of carbon nanotube assemblies.