Article ID Journal Published Year Pages File Type
1416469 Carbon 2011 10 Pages PDF
Abstract

A simple method for extracting otherwise insoluble fullerenes into organic solvents is presented. The fullerenes are reduced to anionic charge states by contact with zinc in the presence of an alkylphosphonium salt in tetrahydrofuran. The anionic fullerenes become soluble, and the non-fullerene carbon matrix is separated by filtration. The anionic fullerenes can then be precipitated from solution by the action of a chemical oxidant such as iodine. It is also shown that there are approximately as many fullerenes left behind in carbon arc soot after solvent extraction as are extracted by the solvent. In contrast, more than twice as many fullerenes are left behind in combustion-produced fullerene soot as are solvent-extracted. Thus, approximately 70% of the total recovered carbon product from large-scale combustion synthesis is fullerenes. Conversely, no detectable amount of fullerenes can be recovered from conventional carbon blacks under the same conditions. Analysis by single photon ionization mass spectrometry suggests that C60 and C70 account for almost half of the fullerenes that were not solvent-extractable, suggesting that they are readily incorporated into toluene-insoluble fullerene polymers. The redox process presented here is easily up-scaled, and we routinely recover 100 g of heretofore insoluble fullerenes in 8 h.

Graphical abstractSingle photon ionization mass spectrometry shows that the chemical redox process presented herein recovers giant fullerenes out to at least 230 atoms, as well as small-gap fullerenes such as C74. C60 and C70 account for almost half of the redox-recovered fullerenes that were not extracted in refluxing solvents.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► A chemical redox process for recovery of fullerenes from soot is described. ► Fullerenes are 70% of the product from large-scale combustion synthesis. ► Solvent extraction recovers only about half of the fullerenes from arc soot. ► Half of the fullerenes that were not solvent-extractable are C60 and C70. ► No fullerenes were recovered from carbon black.

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Physical Sciences and Engineering Energy Energy (General)
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