Abstract A simple and effective method of producing pristine graphene sheets was investigated in this study. Natural graphite flakes were exfoliated in CO2 expanded N-methylpyrrolidone with a low speed agitation of 1000 rpm followed by 30min sonication. Few-layer graphene were obtained with the concentration of 0.0576 mg/mL after centrifugation at 4000 rpm for 30min. More than 90% of the product were two or three-layer graphene and 12–38% were even monolayer. In addition, ethylene glycol and ethanol were also proved to be effective solvents with the assistance of CO2 intercalation, but they were not good solvents for the exfoliation in the subsequent sonication process. Finally, Agitation time, the system pressure and temperature were systemically investigated to find out more appropriate parameters for the production.

中文翻译：

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石墨在 CO 2 膨胀有机溶剂中的剥离结合低速剪切混合

摘要 本研究研究了一种简单有效的原始石墨烯片生产方法。天然石墨薄片在 CO2 膨胀的 N-甲基吡咯烷酮中以 1000 rpm 的低速搅拌剥离，然后进行 30 分钟的超声处理。4000rpm离心30分钟后得到浓度为0.0576mg/mL的少层石墨烯。超过 90% 的产品是两层或三层石墨烯，12-38% 甚至是单层。此外，乙二醇和乙醇也被证明是CO2嵌入辅助的有效溶剂，但它们不是后续超声处理过程中剥离的良好溶剂。最后，对搅拌时间、系统压力和温度进行了系统研究，以找出更适合生产的参数。