In situ observation of graphene sublimation and multi-layer edge reconstructions
In situ observation of graphene sublimation and multi-layer edge reconstructions
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DOI：
10.1073/pnas.0905193106
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发表时间：
2009-06-23
影响因子：
11.1
通讯作者：
Li, Ju
中科院分区：
文献类型：
--
作者：
Huang, Jian Yu;Ding, Feng;Li, Ju
我们在透射电子显微镜内通过原位焦耳加热诱导悬浮的少层石墨烯升华。石墨烯升华前沿主要由{1100}锯齿形边缘组成。在适当的条件下，观察到分形状的“海岸线”形态。在石墨烯边缘的大量多层重构导致了独特的碳纳米结构的形成，例如sp（2）键合的双层边缘（BLE）和连接到BLE的纳米管。还观察到平坦的富勒烯/纳米豆荚和纳米管隧穿多层石墨烯片。值得注意的是，在升华过程中观察到的>99%的石墨烯边缘是BLE而不是单层边缘（MLE），表明BLE是高温下石墨烯中的稳定边缘。我们再现了“海岸线”升华形态的动力学蒙特卡罗（kMC）模拟。模拟揭示了准二维（2D）石墨烯升华和重建所特有的几何和拓扑特征。这些重建是通过弯曲实现的，这在3D块状材料的一阶相变中是不会发生的。这些结果表明，多层石墨烯衬底可以为定制碳基纳米结构和工程设计具有复杂拓扑结构的新型纳米器件提供独特的机会。
We induced sublimation of suspended few-layer graphene by in situ Joule-heating inside a transmission electron microscope. The graphene sublimation fronts consisted of mostly {1100} zigzag edges. Under appropriate conditions, a fractal-like "coastline'' morphology was observed. Extensive multiple-layer reconstructions at the graphene edges led to the formation of unique carbon nanostructures, such as sp(2)-bonded bilayer edges (BLEs) and nanotubes connected to BLEs. Flat fullerenes/nanopods and nanotubes tunneling multiple layers of graphene sheets were also observed. Remarkably, >99% of the graphene edges observed during sublimation are BLEs rather than monolayer edges (MLEs), indicating that BLEs are the stable edges in graphene at high temperatures. We reproduced the "coastline'' sublimation morphologies by kinetic Monte Carlo (kMC) simulations. The simulation revealed geometrical and topological features unique to quasi-2-dimensional (2D) graphene sublimation and reconstructions. These reconstructions were enabled by bending, which cannot occur in first-order phase transformations of 3D bulk materials. These results indicate that substrate of multiple-layer graphene can offer unique opportunities for tailoring carbon-based nanostructures and engineering novel nano-devices with complex topologies.