Electrochemical charge-transfer resistance in carbon nanotube composites.
basic_science · Level V
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- Record sourced from PubMed, PMID 24527984.
- Also identified by DOI 10.1021/nl404349g.
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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.