Extraction of Linear Carbon Chains Unravels the Role of the Carbon Nanotube Host

TL;DR

This study demonstrates a method to extract and separate long linear carbon chains from carbon nanotubes, revealing their optical properties and interactions, which advances potential applications of these nanomaterials.

Contribution

The paper introduces a combined tip-ultrasonic and density gradient ultracentrifugation process for isolating long linear carbon chains from carbon nanotubes, enabling detailed study of their properties.

Findings

Long LCCs can be extracted and separated from DWCNTs.

The Raman spectral frequency of LCCs remains stable regardless of the outer tube.

The extraction method allows potential complete isolation of LCCs from CNTs.

Abstract

Linear carbon chains (LCCs) have been shown to grow inside double-walled carbon nanotubes (DWCNTs) but isolating them from this hosting material represents one of the most challenging tasks towards applications. Herein we report the extraction and separation of LCCs inside single-wall carbon nanotubes (LCCs@SWCNTs) extracted from a double walled host LCCs@DWCNTs by applying a combined tip-ultrasonic and density gradient ultracentrifugation (DGU) process. High-resolution transmission electron microscopy (HRTEM), optical absorption, and Raman spectroscopy show that not only short LCCs but clearly long LCCs (LLCCs) can be extracted and separated from the host. Moreover, the LLCCs can even be condensed by DGU. The Raman spectral frequency of LCCs remains almost unchanged regardless of the presence of the outer tube of the DWCNTs. This suggests that the major importance of the outer tubes is making the whole synthesis viable. We have also been able to observe the interaction between the LCCs and the inner tubes of DWCNTs, playing a major role in modifying the optical properties of LCCs. Our extraction method suggests the possibility towards the complete isolation of LCCs from CNTs.