Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling
Exfoliation Behavior of Large Anionic Graphite Flakes in Liquid Produced by Salt-Assisted Ball Milling
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DOI：
10.3390/pr8010028
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发表时间：
2019-12
期刊：
影响因子：
3.5
通讯作者：
Y. Arao;Jonathon D. Tanks;Kojiro Aida;M. Kubouchi
中科院分区：
文献类型：
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作者：
Y. Arao;Jonathon D. Tanks;Kojiro Aida;M. Kubouchi
石墨的功能化是实现石墨烯高效剥离的关键。当负电荷固定在天然石墨的边缘时，得到的阴离子石墨在极性溶剂中呈现负电荷。这种增强的负电荷被认为是在液相剥落（LPE）过程中石墨剥落的原因。在本研究中，我们采用盐辅助球磨法制备了大阴离子石墨片（~10 μm），并与相同尺寸的天然石墨片进行了比较。在LPE过程中，离心速度和溶剂类型对石墨烯的浓度和质量（如尺寸和厚度）有主要影响，因此我们详细研究了这些因素对阴离子石墨薄片的影响。阴离子石墨在各种溶剂（异丙醇、甲乙基酮、丙酮和水基助溶剂）中的剥离效率均高于天然石墨。单层石墨烯的平均尺寸为80-200 nm，仅在3 min的超声下就获得了相对较高的收率（bbb10 %）。石墨烯的小尺寸是由于LPE过程中边缘破碎造成的。研究了沉淀物的可回收性和脱落的阴离子石墨烯粉末的表征。
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.