Separation of Specific Single Enantiomer Single-Wall Carbon Nanotubes in the Large Diameter Regime
Jeffrey A. Fagan, Ming Zheng, Sofie Cambre, Wim Wenseleers, Benjamin Flavel, Han Li, Stephanie Reich, Georgy Gordeev, Oisin Garrity, Naga Peyyety, Ralph Krupke, Pranauv Selvasundaram
Enantiomer level isolation of single-wall carbon nanotubes (SWCNTs) in high concentration and purity for nanotubes greater than 1.1 nm in diameter is demonstrated for the first time using a twostage aqueous two-phase extraction (ATPE) technique. In total 5 different nanotube species of 1.41 nm diameter are isolated, including both metallics and semiconductors. We characterize these populations by absorbance spectroscopy, circular dichroism spectroscopy, resonance Raman spectroscopy and photoluminescence mapping, revealing and substantiating mod-dependent optical dependencies. Using knowledge of the competitive adsorption of surfactants to the SWCNTs that controls partitioning within the ATPE separation we describe an advanced acid addition methodology that enables the fine control of the separation for these select nanotubes. Furthermore, we show that endohedral filling is a previously unrecognized but important factor to ensure a homogenous starting-material and further enhance separation yield, with best results for alkane-filled SWCNTs, followed by empty SWCNTs with the intrinsic inhomogeneity of water-filled SWCNTs causing them to be worst for separations. Lastly, we demonstrate the potential use of these nanotubes in field-effect transistors.