Light-Induced Sulfur Transport inside Single-Walled Carbon Nanotubes.

Olga Sedelnikova,Anastasiya Fedorenko,Pavel Plyusnin,Anna Makarova,Raul Arenal,Anton Nikolenko,Alexander Okotrub,Olga Gurova,Lyubov Bulusheva

doi:10.3390/nano10050818

Abstract

Filling of single-walled carbon nanotubes (SWCNTs) and extraction of the encapsulated species from their cavities are perspective treatments for tuning the functional properties of SWCNT-based materials. Here, we have investigated sulfur-modified SWCNTs synthesized by the ampoule method. The morphology and chemical states of carbon and sulfur were analyzed by transmission electron microscopy, Raman scattering, thermogravimetric analysis, X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopies. Successful encapsulation of sulfur inside SWCNTs cavities was demonstrated. The peculiarities of interactions of SWCNTs with encapsulated and external sulfur species were analyzed in details. In particular, the donor–acceptor interaction between encapsulated sulfur and host SWCNT is experimentally demonstrated. The sulfur-filled SWCNTs were continuously irradiated in situ with polychromatic photon beam of high intensity. Comparison of X-ray spectra of the samples before and after the treatment revealed sulfur transport from the interior to the surface of SWCNTs bundles, in particular extraction of sulfur from the SWCNT cavity. These results show that the moderate heating of filled nanotubes could be used to de-encapsulate the guest species tuning the local composition, and hence, the functional properties of SWCNT-based materials.

Highlights

Carbon nanotubes (CNTs) are an ideal material for filling of their empty cavities with different species
Materials containing sulfur and single-walled carbon nanotubes (SWCNTs) have been obtained by the ampoule synthesis
transmission electron microscopy (TEM), Raman, TG and X-ray data showed that sulfur effectively encapsulated inside SWCNTs, while, in the presence of residual catalyst particles, a significant proportion of sulfur is consumed on the formation of iron sulfides

Summary

Introduction

Carbon nanotubes (CNTs) are an ideal material for filling of their empty cavities with different species. The enhancement of optoelectronic properties of single-walled carbon nanotubes (SWCNTs) through controlled encapsulation and de-encapsulation of guest molecules from their cavities by choosing of an appropriate solvent was discussed in Ref [11]. Another approach is associated with the impact of high-energy irradiations on nanotubes. Electron beam irradiation of CNTs filled with CuI caused removal of iodine and formation of a copper core, which should endow the material with different functionalities [20]. The other example is drug release from encapsulating CNTs to target the cancer cell under heating [21,22,23]

Methods

Results

Conclusion