Coalescence of carbon nanotubes while preserving the chiral angles

Abstract

カーボンナノチューブを融合して直径2倍のチューブへと効率よく変換 --太いナノチューブの構造制御や後処理による物性改変に道-- . 京都大学プレスリリース. 2025-02-06.Atomically precise coalescence of graphitic nanocarbon molecules is one of the most challenging reactions in sp² carbon chemistry. Here, we demonstrate that two carbon nanotubes with the same chiral indices (n, m) are efficiently coalesced into a single (2n, 2 m) nanotube with preserved chiral angles via heat treatment at less than 1000 °C. The (2n, 2 m) nanotubes constitute up to ≈ 20%–40% of the final sample in the most efficient case. Additional optical absorption peaks of the (2n, 2 m) nanotubes emerge, indicating that the reaction occurs over the entire sample. The reaction efficiency strongly depends on the chiral angle, implying that C–C bond cleavage and recombination occurs sequentially. Furthermore, the reaction occurs efficiently even at 600 °C in an atmosphere containing trace amounts of oxygen. These findings offer routes for the structure-selective synthesis of large-diameter nanotubes and modification of the properties of nanotube assemblies via postprocessing