1D van der Waals heterostructures based on single-walled carbon nanotubes encapsulating linear carbon chains: Stability and charge transfer evidence from Raman spectroscopy

Abstract

The emerging one-dimensional van der Waals heterostructures (1D vdWHTs) are raising a lot of enthusiasm due to the possibilities for creating novel physical properties. In this paper, we focus on single-walled carbon nanotubes (SWCNTs) encapsulating a series of hydrogen-terminated linear carbon chains (LCCs) of lengths ranging from 4 up to 40 carbon atoms as a template for 1D vdWHTs (LCCs@SWCNTs). We explored the structural properties and stability of the LCCs@SWCNTs systems. The optimal SWCNT diameter for which the resulting 1D vdWHTs are stable is determined using Lennard-Jones (LJ) potential. SWCNTs with diameters of around 0.75 nm are found most convenient to accommodate LCCs. Combining the molecular dynamics (MD), the density functional theory (DFT), bond polarizability model (BPM), and the spectral moment’s method (SMM), we computed the Raman spectra of the free LCCs and LCCs@(6,5) 1D vdWHTs. The stability and charge transfer in the LCCs@(6,5) systems are evinced by analyzing the Raman active modes of the LCCs, as well as the radial breathing mode (RBM) and G-band of the (6,5) SWCNT before and after filling. These findings provide benchmark theoretical data to understand both the Raman data of the LCCs and the confinement effect on those of the SWCNTs encasing LCCs which have not been clearly addressed before.