Dispersion and Separation of Single‐Walled Carbon Nanotubes

Abstract

Recently, gel chromatography has been demonstrated as an effective method for the separation of single-walled carbon nanotubes (SWCNTs) according to their electronic type and structure. The separation of SWCNTs was thought to result from the different affinity forces between the gel and various SWCNTs. Based on this method, we investigated the effect of ultrasonic time on the dispersion and separation of metallic and semiconducting SWCNTs. At a low ultrasonic power, with the increase of ultrasonic time, better monodispersed SWCNTs in sodium dodecylsulfate (SDS) aqueous solution were obtained. The UV-visible-near infrared (UV-Vis-NIR) absorption, Raman and photoluminescence (PL) spectroscopic characterizations confirmed that under the condition of ultrasonication (2 h), higher-purity metallic tubes and semiconducting tubes with different diameter distributions could be obtained. We believe that the control of the ultrasonication time may tune the mono-dispersity and the length of SWCNTs, which would further influence the difference in affinity forces between various SWCNTs and the gel, therefore leading to different separation results.

Enhanced Photoinduced Electron-Transfer Reduction of Li+@C60in Comparison with C60

“…Fullerenes have attracted considerable interest for a wide range of practical applications because of the unique electrical and chemical properties, in particular the excellent electron-transfer properties at the ground and photoexcited states. − Because fullerenes have spacious inner cavities, some metals can be encapsulated inside the fullerene cages to form endohedral metallofullerenes. − The metal(s) are normally encapsulated in fullerenes having higher cages (so-called higher fullerenes such as C 72 , C 80 and C 82 ), in which the fullerene cage is reduced by encapsulated metals. − As a typical metallofullerene, La@C 82 has a La 3+ in a three-electron reduced C 82 trianion radical cage. − On the other hand, lithium ion-encapsulated C 60 (Li + @C 60 ) was recently isolated, and the X-ray crystal structure was determined. , In the case of Li + @C 60 , the C 60 cage remains neutral . The electron acceptor ability of Li + @C 60 was significantly enhanced as compared to pristine C 60 . − The enhanced electron acceptor ability of Li + @C 60 has made it possible to form a supramolecular electron-transfer complex between a tetrathiafulvalene calix[4]pyrrole (TTF-C4P) and Li + @C 60 with chloride anion .…”

Small Reorganization Energies of Photoinduced Electron Transfer between Spherical Fullerenes

“…Thus, fullerene has been frequently employed as an efficient electron acceptor for the donor–acceptor charge-separation systems. − On the Marcus theory of intermolecular electron transfer, the solvent reorganization energy was calculated by assuming that the electron donor and acceptor molecules are spheres. , Because C 60 is virtually spherical, it is an ideal molecule to examine the electron-transfer reactions involving C 60 in light of the Marcus theory of electron transfer. Because fullerenes have spacious inner cavities, some metals can be encapsulated inside of the fullerene cages to form endohedral metallofullerenes. − Such endohedral fullerenes have recently gained increasing attention with regard to the potential applicability due to the specific reactivities, being spherical molecules ( I h - symmetry) like C 60 . For instance, lithium ion-encapsulated C 60 fullerene (Li + @C 60 ) has an I h -symmetric C 60 cage.…”