Double-walled carbon nanotubes: Quantitative purification assessment, balance between purification and degradation and solution filling as an evidence of opening
Résumé
We compared the effect of different oxidizing agents on purification, functionalization and
opening of double-walled carbon nanotubes. The oxidative treatments were realized in
nitric acid solutions at different concentrations (3 M or 15 M), in a mixture of two oxoacids
(conc. HNO3/conc. H2SO4) or in sulphuric acid solutions of KMnO4 or K2Cr2O7. Most of these
treatments were very efficient for purification (removal of residual catalytic metal nanoparticles
and/or of disorganized carbon) but also caused secondary reactions such as shortening
of the nanotubes, creation of functionalized amorphous carbon deposits and covalent
functionalization of the outer wall. Secondary treatments were undertaken in order to
remove functionalized carbon deposit by washing with sodium hydroxide solutions or by
heat treatment in air. A partial filling in solution was obtained with uranyl nitrate, in order
to evidence the opening of carbon nanotubes. Effects of purification and filling treatments
were characterized both qualitatively by TEM and HRTEM, AFM and Raman spectroscopy,
and quantitatively by elemental chemical analysis and chemical titrations.
Domaines
Matériaux
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