Analysis of kinetics and selectivity for the reaction of single-walled carbon nanotubes with 4-hydroxybenzene diazonium salts

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Woo-Jae Kim, wjkim@uiuc.edu, Nitish Nair, nnair2@uiuc.edu, Monica L. Usrey, usrey@uiuc.edu, and Michael S. Strano, strano@uiuc.edu. Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801
Diazonium salts are reported to selectively react with metallic single-walled carbon nanotubes (SWNTs) over semiconducting SWNTs. In this study, we investigated the reaction kinetics of SWNT mixtures with 4-hydroxybenzene diazonium salts under various experimental conditions and analyzed their influence on the reaction selectivity using UV-Vis-nIR absorption spectroscopy. Metallic SWNTs reacted preferentially with diazonium salts over semiconducting SWNTs at low salt concentrations with a maximum selectivity of 76%. However, the selectivity was drastically lowered at high salt concentrations, as the semiconducting SWNTs as well as metallic reacted with diazonium salts. Furthermore, this reaction was shown to be light-sensitive. Both the selectivity and activity were increased upon illumination, indicating that the type of diazonium intermediate affects the reaction kinetics. Reaction rate constants of individual (n,m) SWNTs were also calculated by deconvolution of the absorption spectra.