Double-and triple-walled carbon nanotubes (DWNTs and TWNTs) consist of coaxially-nested two and three single-walled carbon nanotubes (SWNTs). They act as the geometrical bridge between SWNTs and multi-walled carbon nanotubes (MWNTs), providing an ideal model for studying the coupling interactions between different shells in MWNTs. Within this context, this article comprehensively reviews various synthetic routes of DWNTs' and TWNTs' production, such as arc discharge, catalytic chemical vapor deposition and thermal annealing of pea pods (i.e., SWNTs encapsulating fullerenes). Their structural features, as well as promising applications and future perspectives are also discussed.
Linear carbon chains (LCCs) consisting of sp-hybridized carbon atoms are considered a fascinating 1D system and could be used in the fabrication of the next-generation molecular devices because of its ideal linear atomic nature. A large portion of long LCCs inside multi-walled carbon nanotubes (MWCNTs) were synthesized by atmospheric arc discharge in the presence of boron. Closed-end growth of MWCNTs in the arc process is suggested as a critical condition for the simultaneous growth of LCCs within the inner cores of carbon nanotubes. The strong Raman line around 1850 cm-1 was used to characterize the degree of *Manuscript Click here to view linked References
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