title: Electrochemical charge-transfer resistance in carbon nanotube composites.
abstract: Using a model system of single, isolated carbon nanotubes loaded with high-capacitance metal-oxide films, we have quantitatively investigated electrochemical composites on the single-nanotube scale. Electrochemical charging and discharging of a model MnO2 storage material was used to probe interfacial charge transfer and surface impedances at the nanotube interface. We found that one single-walled carbon nanotube has an apparent surface resistivity of 30 mΩ cm(2), approximately 4 times smaller than for a multiwalled carbon nanotube and 50 times smaller than the 1.5 Ω cm(2) resistivity of Pt or graphite films. The improvement originates in the electrochemical-transport properties of microelectrodes shrunk to a nanotube's dimensions rather than any unique nanotube property like curvature, bandstructure, or surface chemistry. In explaining the enhanced performance of certain nanotube-containing composites, the results overturn widely held assumptions about nanotubes' roles while also providing guidelines for optimizing effective composites.
authors: Department of Physics and Astronomy, University of California at Irvine , Irvine, California 92697, United States.
authors: Brad L
authors: BL
authors: Corso
authors: Israel
authors: I
authors: Perez
authors: Tatyana
authors: T
authors: Sheps
authors: Patrick C
authors: PC
authors: Sims
authors: O Tolga
authors: OT
authors: Gül
authors: Philip G
authors: PG
authors: Collins