Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling
Functionalization of graphite is crucial for efficient and effective exfoliation to graphene. When negative charges are fixed to the edges of natural graphite, the resulting anionic graphite shows negative charging in a polar solvent. This enhanced negative charging is assumed to contribute the exfo...
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doaj-de2f824be4654859aaeb9bae609766ca2020-11-25T02:03:25ZengMDPI AGProcesses2227-97172019-12-01812810.3390/pr8010028pr8010028Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball MillingYoshihiko Arao0Jonathon D. Tanks1Kojiro Aida2Masatoshi Kubouchi3School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro, Tokyo 152-8550, JapanNational Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, JapanSchool of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro, Tokyo 152-8550, JapanSchool of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro, Tokyo 152-8550, JapanFunctionalization of graphite is crucial for efficient and effective exfoliation to graphene. When negative charges are fixed to the edges of natural graphite, the resulting anionic graphite shows negative charging in a polar solvent. This enhanced negative charging is assumed to contribute the exfoliation of graphite during liquid-phase exfoliation (LPE). In this study, we prepared large anionic graphite flakes (~10 μm) by salt-assisted ball milling, as well as natural graphite flakes of the same size for comparison. During the LPE process, centrifugation speed and solvent type have dominant effects on graphene concentration and quality (e.g., size and thickness), so we investigated these factors for anionic graphite flakes in detail. The anionic graphite showed higher exfoliation efficiency in every type of solvent (isopropanol, methyl ethyl ketone, acetone, and water-based cosolvent) compared with the natural graphite. Monolayer graphene, with an average size of 80−200 nm, was obtained with relatively high yield (>10%) at only 3 min of sonication. The small size of graphene was due to edge fragmentation during the LPE process. The recyclability of the sediment and the characterization of the exfoliated powders for anionic graphene were also investigated.https://www.mdpi.com/2227-9717/8/1/28grapheneliquid-phase exfoliationgraphite structurecharacterization |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Yoshihiko Arao Jonathon D. Tanks Kojiro Aida Masatoshi Kubouchi |
spellingShingle |
Yoshihiko Arao Jonathon D. Tanks Kojiro Aida Masatoshi Kubouchi Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling Processes graphene liquid-phase exfoliation graphite structure characterization |
author_facet |
Yoshihiko Arao Jonathon D. Tanks Kojiro Aida Masatoshi Kubouchi |
author_sort |
Yoshihiko Arao |
title |
Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling |
title_short |
Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling |
title_full |
Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling |
title_fullStr |
Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling |
title_full_unstemmed |
Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling |
title_sort |
exfoliation behavior of large anionic graphite flakes in liquid produced by salt-assisted ball milling |
publisher |
MDPI AG |
series |
Processes |
issn |
2227-9717 |
publishDate |
2019-12-01 |
description |
Functionalization of graphite is crucial for efficient and effective exfoliation to graphene. When negative charges are fixed to the edges of natural graphite, the resulting anionic graphite shows negative charging in a polar solvent. This enhanced negative charging is assumed to contribute the exfoliation of graphite during liquid-phase exfoliation (LPE). In this study, we prepared large anionic graphite flakes (~10 μm) by salt-assisted ball milling, as well as natural graphite flakes of the same size for comparison. During the LPE process, centrifugation speed and solvent type have dominant effects on graphene concentration and quality (e.g., size and thickness), so we investigated these factors for anionic graphite flakes in detail. The anionic graphite showed higher exfoliation efficiency in every type of solvent (isopropanol, methyl ethyl ketone, acetone, and water-based cosolvent) compared with the natural graphite. Monolayer graphene, with an average size of 80−200 nm, was obtained with relatively high yield (>10%) at only 3 min of sonication. The small size of graphene was due to edge fragmentation during the LPE process. The recyclability of the sediment and the characterization of the exfoliated powders for anionic graphene were also investigated. |
topic |
graphene liquid-phase exfoliation graphite structure characterization |
url |
https://www.mdpi.com/2227-9717/8/1/28 |
work_keys_str_mv |
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