文摘
We studied the transition from the electrochemical double-layer charging regime to intercalative doping ofbundled single-walled carbon nanotubes (SWNT) in KCl and HCl aqueous solution. For this purpose weused high doping levels by applying constant potentials above 1000 mV approaching and slightly exceedingthe oxidation potential for Cl- ions. At each potential in situ Raman measurements of the radial breathingmode (RBM), the high-energy tangential mode (HEM), and the disorder-induced (D) mode were performed.Furthermore, the conductivity and reflectivity of a set of SWNT samples were measured as a function ofdoping and subsequently the samples were examined by X-ray photoelectron spectroscopy (XPS). From acomparative analysis of the results we conclude that above 1000 mV a significant penetration of chlorinespecies into the interstitial channels of the SWNT bundles and possible covalent functionalization take place.