He Kuang, Robertson Alex W, Lee Sungwoo, Yoon Euijoon, Lee Gun-Do, Warner Jamie H
Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom.
ACS Nano. 2014 Dec 23;8(12):12272-9. doi: 10.1021/nn504471m. Epub 2014 Nov 25.
Graphene has three experimentally confirmed periodic edge terminations, zigzag, reconstructed 5-7, and arm-chair. Theory predicts a fourth periodic edge of graphene called the extended Klein (EK) edge, which consists of a series of single C atoms protruding from a zigzag edge. Here, we confirm the existence of EK edges in both graphene nanoribbons and on the edge of bulk graphene using atomic resolution imaging by aberration-corrected transmission electron microscopy. The formation of the EK edge stems from sputtering and reconstruction of the zigzag edge. Density functional theory reveals minimal energy for EK edge reconstruction and bond distortion both in and out of plane, supporting our TEM observations. The EK edge can now be included as the fourth member of observed periodic edge structures in graphene.
石墨烯有三种经实验证实的周期性边缘终止结构，即锯齿形、重构的5-7结构和扶手椅形。理论预测石墨烯存在第四种周期性边缘，称为扩展克莱因（EK）边缘，它由从锯齿形边缘突出的一系列单个碳原子组成。在此，我们通过像差校正透射电子显微镜的原子分辨率成像，证实了石墨烯纳米带和块状石墨烯边缘均存在EK边缘。EK边缘的形成源于锯齿形边缘的溅射和重构。密度泛函理论揭示了EK边缘重构以及平面内外键畸变的最小能量，支持了我们的透射电子显微镜观测结果。EK边缘现在可被纳入石墨烯中观察到的周期性边缘结构的第四个成员。
