Diameter-Selective Electrochemical Doping of HiPco Single-Walled Carbon Nanotubes

Abstract

Electrochemical doping of HiPco nanotubes was studied in acetonitrile solution containing four different electrolytes (LiClO4, NMe4BF4, NBu4ClO4, and NOct4ClO4 (Me = methyl, Bu = butyl, Oct = octyl) and in two ionic liquids (1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate). In situ Raman spectroelectrochemistry confirms the diameter-selective loss of Raman resonance upon doping: nanotubes having diameters between 1 and 1.2 nm are less affected by doping than both narrower and wider tubes. The counterions, which compensate for the electronic charge in the solid, also influence the doping efficiency. The less-pronounced doping was traced for 1-butyl-3-methylimidazolium cations.