Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan.
ACS Nano. 2011 Mar 22;5(3):2332-9. doi: 10.1021/nn200025p. Epub 2011 Feb 10.
Flexible and ultratransparent conductors based on graphene sheets have been considered as one promising candidate for replacing currently used indium tin oxide films that are unlikely to satisfy future needs due to their increasing cost and losses in conductivity on bending. Here we demonstrate a simple and fast electrochemical method to exfoliate graphite into thin graphene sheets, mainly AB-stacked bilayered graphene with a large lateral size (several to several tens of micrometers). The electrical properties of these exfoliated sheets are readily superior to commonly used reduced graphene oxide, which preparation typically requires many steps including oxidation of graphite and high temperature reduction. These graphene sheets dissolve in dimethyl formamide (DMF), and they can self-aggregate at air-DMF interfaces after adding water as an antisolvent due to their strong surface hydrophobicity. Interestingly, the continuous films obtained exhibit ultratransparency (∼96% transmittance), and their sheet resistance is <1k Ω/sq after a simple HNO3 treatment, superior to those based on reduced graphene oxide or graphene sheets by other exfoliation methods. Raman and STM characterizations corroborate that the graphene sheets exfoliated by our electrochemical method preserve the intrinsic structure of graphene.
基于石墨烯片的柔韧和超高透明导体已被认为是一种有前途的替代目前使用的氧化铟锡（ITO）薄膜的候选材料，因为ITO 薄膜的成本不断增加，且在弯曲时导电性会损失，不太可能满足未来的需求。在这里，我们展示了一种简单而快速的电化学方法，将石墨剥离成薄的石墨烯片，主要是 AB 堆叠的双层石墨烯，具有较大的横向尺寸（几到几十微米）。这些剥离片的电学性能明显优于常用的还原氧化石墨烯（rGO），rGO 的制备通常需要多个步骤，包括石墨的氧化和高温还原。这些石墨烯片可溶解于二甲基甲酰胺（DMF）中，在加入水作为反溶剂后，它们会在空气-DMF 界面处自组装，这是由于其强烈的表面疏水性。有趣的是，所获得的连续薄膜表现出超高透明度（约 96%透光率），并且在经过简单的 HNO3 处理后，其方阻<1kΩ/sq，优于基于还原氧化石墨烯或其他剥离方法得到的石墨烯片的方阻。拉曼和 STM 表征证实了我们的电化学方法剥离的石墨烯片保留了石墨烯的本征结构。
