A single-step room-temperature electrochemical synthesis of nitrogen-doped graphene nanoribbons from carbon nanotubes

Multiwalled carbon nanotubes (MWCNTs) were transformed into nitrogen-doped graphene/graphitic nanoribbons (N-doped GNRs) in a single-step electrochemical process at room temperature in formamide, which acts as a solvent and a source of nitrogen. The N-doped GNRs, with about 4 at% pyridinic and pyrrolic nitrogens, were characterized by transmission electron microscopy, atomic force microscopy, Raman spectrometry, infra-red spectrophotometry, X-ray photoelectron spectroscopy and cyclic voltammetry. Nitrogen doping can be regulated by varying the applied electric field or the duration of the reaction, wherein the kinetics of decomposition of formamide plays a critical role. N-doped GNRs show enhanced charge storage ability, attributed mainly to the increased surface area resulting from a change in morphology when cylindrical MWCNTs are sequentially unzipped as well as to a possible pseudocapacitance contribution from pyridinic and pyrrolic nitrogens. This unprecedented synthetic route provides a room-temperature method for the production of high quality, N-doped GNRs with specific nitrogen types for a variety of applications.