title: A simple road for the transformation of few-layer graphene into MWNTs.
abstract: We report the direct formation of multiwalled carbon nanotubes (MWNT) by ultrasonication of graphite in dimethylformamide (DMF) upon addition of ferrocene aldehyde (Fc-CHO). The tubular structures appear exclusively at the edges of graphene layers and contain Fe clusters. Fc in conjunction with benzyl aldehyde, or other Fc derivatives, does not induce formation of NT. Higher amounts of Fc-CHO added to the dispersion do not increase significantly MWNT formation. Increasing the temperature reduces the amount of formation of MWNTs and shows the key role of ultrasound-induced cavitation energy. It is concluded that Fc-CHO first reduces the concentration of radical reactive species that slice graphene into small moieties, localizes itself at the edges of graphene, templates the rolling up of a sheet to form a nanoscroll, where it remains trapped, and finally accepts and donates unpaired electron to the graphene edges and converts the less stable scroll into a MWNT. This new methodology matches the long held notion that CNTs are rolled up graphene layers. The proposed mechanism is general and will lead to control the production of carbon nanostructures by simple ultrasonication treatments.
authors.affiliation: Center of Excellence for Nanostructured Materials and INSTM, unit of Trieste, Dipartimento di Scienze Chimiche e Farmaceutiche, University of Trieste, Piazzale Europa 1, I-34127 Trieste, Italy. mildred@ifisica.uaslp.mx
authors.forename: Mildred
authors.initials: M
authors.lastname: Quintana
authors.forename: Marek
authors.initials: M
authors.lastname: Grzelczak
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Spyrou
authors.forename: Matteo
authors.initials: M
authors.lastname: Calvaresi
authors.forename: Sara
authors.initials: S
authors.lastname: Bals
authors.forename: Bart
authors.initials: B
authors.lastname: Kooi
authors.forename: Gustaaf
authors.initials: G
authors.lastname: Van Tendeloo
authors.forename: Petra
authors.initials: P
authors.lastname: Rudolf
authors.forename: Francesco
authors.initials: F
authors.lastname: Zerbetto
authors.forename: Maurizio
authors.initials: M
authors.lastname: Prato