Synthesis, enhanced stability and structural imaging of C< sub> 60 and C< sub> 70 double-wall carbon nanotube peapods (original) (raw)
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Fullerene-peapods: Synthesis, structure, and Raman spectroscopy
AIP Conference Proceedings, 2001
Single-wall carbon nanotubes (SWNTs) encapsulating fullerenes, so-called fullerenepeapods, were synthesized in high yield by using diameter-selected nanotubes as pods. Highresolution transmission electron microscopy revealed high-density fullerene chains inside nanotubes. X-ray diffraction measurements indicate 60% filling of C 60 molecules in a macroscopic average. Room temperature Raman spectra show one-dimensional photopolymerization of C 60 inside nanotubes by blue laser irradiation, indicating molecular rotation inside. In C 70-peapod case, Raman active modes peculiar to C 70 were strongly suppressed by encapsulation. The suppression is probably caused by deformation of molecule due to the unisotropic interaction between C 70 and SWNT. Anomalous resonance effects in C 70peas suggest hybridization of electronic states of C 70 and nanotubes. High-symmetry mode Raman intensity suggests the filling factor to be higher than 50%, which is consistent with the X ray diffraction analysis.
Fullerene derivatives encapsulated in carbon nanotubes
physica status solidi (b), 2007
We report on the preparation and subsequent Raman analysis of carbon nanotube peapods, using the fullerene C 60 and its heterofullerene derivative (C 59 N) 2 as filling materials. The filling with (C 59 N) 2 was done from liquid solution at room temperature and from the gas phase at elevated temperatures. The success of the encapsulation procedure is confirmed through the identification of fingerprint Raman modes and the conversion to double wall nanotubes through heating to 1250°C. The 2D mode of double wall nanotubes made from (C 59 N) 2 peapods is observed to be downshifted compared to the same mode in double wall nanotubes made from C 60 peapods. We interpret this downshift as an evidence for the integration of the nitrogen into the lattice of the inner tube.
Low temperature fullerene encapsulation in single wall carbon nanotubes: synthesis of N@C60@SWCNT
Chemical Physics Letters, 2004
High filling of single wall carbon nanotubes (SWCNT) with C60 and C70 fullerenes in solvent is reported at temperatures as low as 69 o C. A 2 hour long refluxing in n-hexane of the mixture of the fullerene and SWCNT results in a high yield of C60,C70@SWCNT, fullerene peapod, material. The peapod filling is characterized by TEM, Raman and electron energy loss spectroscopy and X-ray scattering. We applied the method to synthesize the temperature sensitive (N@C60:C60)@SWCNT as proved by electron spin resonance spectroscopy. The solvent prepared peapod samples can be transformed to double walled nanotubes enabling a high yield and industrially scalable production of DWCNT.
Structural and Vibrational Properties of C60 and C70 Fullerenes Encapsulating Carbon Nanotubes
Fullerenes and Relative Materials - Properties and Applications, 2018
Carbon nanotubes (CNTs) can encapsulate small and large molecules, including C 60 and C 70 fullerenes (so-called carbon peapods). The challenge for nanotechnology is to achieve perfect control of nanoscale-related properties, which requires correlating the parameters of synthesis process with the resulting nanostructure. For that purpose, note every conventional characterization technique is suitable, but Raman spectroscopy has already proven to be. First, the different possible configurations of C 60 and C 70 molecules inside CNTs are reviewed. Therefore, the following changes of properties of the empty nanotubes, such as phonon modes, induced by the C 60 and C 70 filling inside nanotube are presented. We also briefly review the concept of Raman spectroscopy technique that provides information on phonon modes in carbon nanopeapods. The dependencies of the Raman spectrum as a function of nanotube diameter and chirality, fullerene molecules configuration and the filling level are identified and discussed. The experimental Raman spectra of fullerenes and fullerenes peapods are discussed in the light of theoretical calculation results. Finally, the variation of the average intensity ratio between C 60 and C 70 Raman-active modes and the nanotube ones, as a function of the concentration molecules, are analyzed, and a general good agreement is found between calculations and measurements.
Spectral properties of single-walled carbon nanotubes encapsulating fullerenes
Carbon, 2007
Single-walled carbon nanotubes (SWCNTs) with diameter ranged from 1.22 to 1.6 nm filled with C 60 , C 70 and C 60 H 28 molecules (peapods), as well as double-walled carbon nanotubes (DWCNTs) derived from peapods, were studied by HRTEM, UV-vis-NIR and Raman spectroscopy. Suspensions with accurate concentration were used for spectroscopic studies to enable quantitative comparison of different substances. Filling of the SWCNTs with C 70 molecules resulted in a reduced van der Waals interaction between the tubes in a bundle. The DWCNTs have lower intensity of the van Hove bands and weaker photoluminescence. Raman spectra at 633 and 1064 nm excitation wavelengths reveal that RBM frequencies of C 60 and C 70 peapods are equally downshifted compared to empty tubes. It was found that filling of the nanotubes with C 60 and C 70 caused spectral shifts of absorption bands: thin tubes display red shifts, while thick ones show blue shifts. DWCNTs and C 60 H 28 @SWCNTs do not show any shifts. All the results suggest that the filling of nanotubes with fullerenes alters the average diameter of the electron cloud around SWCNT framework; namely, it increases for thin SWCNTs, and decreases for thick ones. Our attempts to structurally assign thick nanotubes using reported extrapolations from data for thin tubes were unsuccessful.
C60/collapsed carbon nanotube hybrids: A variant of peapods
We examine a variant of so-called carbon nanotube peapods by packing C60 molecules inside the open edge ducts of collapsed carbon nanotubes. C60 insertion is accomplished through a facile single-step solution-based process. Theoretical modeling is used to evaluate favorable low-energy structural configurations. Overfilling of the collapsed tubes allows infiltration of C60 over the full cross-section of the tubes and consequent partial or complete reinflation, yielding few-wall, large diameter cylindrical nanotubes packed with crystalline C60 solid cores.
The Journal of Physical Chemistry C, 2014
We present compelling evidence pointing to the possible synthesis of unconventional C 66 and C 68 fullerenes in the interior of single-walled carbon nanotubes. The production proceeds from C 60-toluene/benzene clathrates encapsulated inside the nanotubes using heat-driven nano-testtube chemistry. All isomers violate the so-called isolated pentagon rule and are stabilized solely by the proximity of the wall of the host nanotube. We present detailed characterization of the unconventional fullerenes using Raman spectroscopy, 13 C isotope labeling of the benzene molecules, transmission electron microscopy, X-ray diractometry, and rst principles calculations. Multiple isomers of both C 66 and C 68 are identied in the sample. We argue that our method opens the way to high-yield
Physical Review B, 2002
We report recent measurements of the electronic and structural properties of bulk samples of C 60 molecules encapsulated in single-wall carbon nanotubes ͑so-called peapods͒ using electron-energy-loss spectroscopy in transmission. We demonstrate that C 60 peapods with a single-wall carbon nanotube ͑SWNT͒ diameter distribution of 1.37Ϯ0.08 nm have an average fullerene filling of 60%. Regarding the electronic and optical properties, the overall shape of the response of the SWNT and the peapods is very similar, but with distinct differences in the fine structure. The interband transitions of the SWNT are slightly downshifted in the peapods, which can be explained by either a small increase of the SWNT diameter or by a change of the intertube interaction. The electronic and optical properties of the encapsulated C 60 peas closely resemble those of solid fcc C 60 showing small changes in the relative intensities, peak positions, and peak width, which point to a weak van der Waals interaction between the tubes and the encapsulated fullerenes.