Functionalization of carbon materials by reduction of diazonium cations in situ produced in a Brønstedt acidic ionic liquid: an efficient self-patching and self-limiting process

Abstract : The imidazolium-based acidic ionic liquid 1-butyl-3-methylimidazolium hydrogensulfate, [BMIm][HSO4], is used for the grafting of carbon materials, allowing the nitrobenzene diazonium cations to be simply produced in situ. An appealing self-limiting and self-patching process occurs in this viscous ionic liquid. Even for low electrolysis charge consumption, the layers are particularly dense and compact at atomic force microscopy resolution. The grafting method is further extended to carbon nanotubes, following either an electrochemical or a chemical route. A bucky paste is easily obtained from [BMIm][HSO4] and carbon nanotubes that could coat a graphite electrode surface. This simple soft method allows: 1) in situ electrografting of carbon nanotubes in [BMIm][HSO4] and/or 2) easy-to-handle electrochemical characterizations of the functionalized carbon nanotubes. The covalent functionalization of single-walled carbon nanotubes is further assessed by Raman spectroscopy.