Separation of Specific Single-Enantiomer Single-Wall Carbon Nanotubes in the Large-Diameter Regime

The enantiomer-level isolation of single-walledcarbon nanotubes (SWCNTs) in high concentration and withhigh purity for nanotubes greater than 1.1 nm in diameter isdemonstrated using a two-stage aqueous two-phase extraction(ATPE) technique. In total,five different nanotube species of∼1.41 nm diameter are isolated, including both metallics andsemiconductors. We characterize these populations byabsorbance spectroscopy, circular dichroism spectroscopy,resonance Raman spectroscopy, and photoluminescencemapping, revealing and substantiating mod-dependent opticaldependencies. Using knowledge of the competitive adsorptionof surfactants to the SWCNTs that controls partitioning withinthe ATPE separation, we describe an advanced acid additionmethodology that enables thefine control of the separation ofthese select nanotubes. Furthermore, we show that endohedralfilling is a previously unrecognized but important factor toensure a homogeneous starting material and further enhance the separation yield, with the best results for alkane-filledSWCNTs, followed by empty SWCNTs, with the intrinsic inhomogeneity of water-filled SWCNTs causing them to beworse for separations. Lastly, we demonstrate the potential use of these nanotubes infield-effect transistors