Browsing by Author "Headrick, Robert J."

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    Charged iodide in chains behind the highly efficient iodine doping in carbon nanotubes
    (American Physical Society, 2017) Zubair, Ahmed; Tristant, Damien; Nie, Chunyang; Tsentalovich, Dmitri E.; Headrick, Robert J.; Pasquali, Matteo; Kono, Junichiro; Meunier, Vincent; Flahaut, Emmanuel; Monthioux, Marc; Gerber, Iann C.; Puech, Pascal
    The origin of highly efficient iodine doping of carbon nanotubes is not well understood. Relying on first-principles calculations, we found that iodine molecules (I2) in contact with a carbon nanotube interact to form monoiodide or/and polyiodide from two and three I2 as a result of removing electrons from the carbon nanotube (p-type doping). Charge per iodine atom for monoiodide ion or iodine atom at end of iodine chain is significantly higher than that for I2. This atomic analysis extends previous studies showing that polyiodide ions are the dominant dopants. Moreover, we observed isolated I atoms in atomically resolved transmission electron microscopy, which proves the production of monoiodide. Finally, using Raman spectroscopy, we quantitatively determined the doping level and estimated the number of conducting channels in high electrical conductivity fibers composed of iodine-doped double-wall carbon nanotubes.
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    Versatile acid solvents for pristine carbon nanotube assembly
    (AAAS, 2022) Headrick, Robert J.; Williams, Steven M.; Owens, Crystal E.; Taylor, Lauren W.; Dewey, Oliver S.; Ginestra, Cedric J.; Liberman, Lucy; Ya’akobi, Asia Matatyaho; Talmon, Yeshayahu; Maruyama, Benji; McKinley, Gareth H.; Hart, A. John; Pasquali, Matteo; The Smalley Institute for Nanoscale Science and Technology; The Carbon Hub
    Chlorosulfonic acid and oleum are ideal solvents for enabling the transformation of disordered carbon nanotubes (CNTs) into precise and highly functional morphologies. Currently, processing these solvents using extrusion techniques presents complications due to chemical compatibility, which constrain equipment and substrate material options. Here, we present a novel acid solvent system based on methanesulfonic or p-toluenesulfonic acids with low corrosivity, which form true solutions of CNTs at concentrations as high as 10 g/liter (≈0.7 volume %). The versatility of this solvent system is demonstrated by drop-in application to conventional manufacturing processes such as slot die coating, solution spinning continuous fibers, and 3D printing aerogels. Through continuous slot coating, we achieve state-of-the-art optoelectronic performance (83.6 %T and 14 ohm/sq) at industrially relevant production speeds. This work establishes practical and efficient means for scalable processing of CNT into advanced materials with properties suitable for a wide range of applications.