Exfoliation of single-wall carbon nanotubes in aqueous surfactant suspensions: A Raman study

TL;DR

This study investigates how surfactant-assisted aqueous suspensions affect the Raman spectra of single-wall carbon nanotubes, revealing pressure effects, exfoliation behavior, and diameter selectivity.

Contribution

It provides new insights into the Raman spectral changes during exfoliation and the diameter-dependent selectivity of the process.

Findings

RBM upshift due to internal liquid pressure in suspensions

No RBM shift after exfoliation, indicating different effects

Exfoliation selectively targets small-diameter tubes

Abstract

Aqueous suspensions of bundles and individual single-wall carbon nanotubes were prepared with the help of surfactants. We study the changes in the Raman spectra of the suspensions with respect to powders, and of exfoliated tubes with respect to bundles. The radial breathing modes (RBM) upshift in suspensions because of the internal pressure of the liquid. By contrast, no shift is observed in the RBM spectra after exfoliation in the suspensions. However, we demonstrate a selectivity of the exfoliation process for tubes of small diameters.