One-dimensional carbon nanotubes filled Synthesis and Properties of Materials
|Keywords||carbon nanotube filling supercritical fluid supercritical reaction one dimensional material|
The properties of the hybrid products based on 1D-morphology cavity of nanotubes may exhibit differently from the pristine nanotubes and the macroscopic state of the inserted materials. So far, various kinds of materials such as fullerenes, organic molecules, halides, oxides, metals et. al. had been inserted into the nano-cavity. However, extensive application of the filled SWNTs was limited due to the synthetic approaches to the nanotube channels.In this work, we developed a novel, fast and efficient method to synthesize one dimensional nanotube-based materials via supercritical reaction and supercritical fluid. The properties of as-generated materials were characterized by TEM,Raman and XPS. The main results are as follows:1. Different kinds of metals （Ni, Cu, Ag） and fullerenes (C60, C70, C78, C84, Gd@C82, Er@C82, Ho@C82, Y@C82) were successfully inserted into the nanotubes by the technique with various supercritical fluids and supercritical reaction. The filling rates were proved to be more than 99%.2. For the first time, we proved that organic supercritical fluids were good media to synthesize SWNTs-based one dimensional nanomaterials, not only as solvent but also as reaction agent. This technique can be applied to construct new types of nanomaterials if we choose the appropriate supercritical reaction and fluid in the CNTs. The supercritical technique by using organic solvents extended the range and applications of encapsulated nanostructures.3. The interaction between SWNTs and various kinds of fullerenes (C60, C70, C78, C84) and metallofullerenes (Gd@C82, Er@C82, Ho@C82, Y@C82) has been further investigated. The slight blue shift of G-band in Raman spectra with respect to pristine SWNTs was attributed to the charge transfer from SWNTs to fullerenes cage. The obvious RBM shift strongly depended on the distance between the inner wall of the SWNTs and the fullerene cage and also partly associated with the electronic structure of the fullerene. These results indicated that the interaction between fullerenes and SWNTs, which was considered to be the van de walls interaction, can be influenced by the cage size and the kind of fullerenes.4. XANES spectra and the Raman shift of G-band for metal@SWNTs and fullerene@SWNTs suggested there were charge transfer between the encapsulated materials and the SWNTs but in inverse direction. More upshift of the RBM mode for the fullerene@SWNTs than for the metal@SWNTs was probably attributed to the steric hindrance of encapsulated materials. It is concluded that the interaction between guest and host could be influenced by the properties of the filling materials.