Liu Xiangtai, Fang Qinglong, Hu Tingwei, Ma Dayan, Zhang Xiaohe, Liu Shuai, Ma Fei, Xu Kewei
State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, China.
Phys Chem Chem Phys. 2018 Feb 21;20(8):5964-5974. doi: 10.1039/c7cp07338k.
Graphene as the thinnest material has an extremely large specific surface area, and thus the physical properties of graphene based devices should be sensitively dependent on the contacted metals. Moreover, the interfacial interaction between graphene and metals is complicated and it is difficult to probe. In this paper, epitaxial graphene is prepared by thermal decomposition of 6H-SiC(0001), and then Ag is deposited on it. It is found that the morphology and distribution of Ag particles on graphene domains are independent of the graphene thickness. The Ag particles induce the surface enhanced Raman scattering (SERS) effect and the doping effect in epitaxial graphene. The enhancement factor of SERS as well as the splitting of the G band and the shift of the 2D band decreases with increasing graphene thickness, which can be ascribed to the weakened interaction between Ag and EG. This is confirmed by the charge transfer between the Ag atom and epitaxial graphene on 6H-SiC predicted by first-principles calculations. The results are helpful to the design and development of graphene-based composites and devices.
石墨烯作为最薄的材料具有极大的比表面积，因此基于石墨烯的器件的物理性质应敏感地依赖于所接触的金属。此外，石墨烯与金属之间的界面相互作用很复杂且难以探测。在本文中，通过6H-SiC(0001)的热分解制备外延石墨烯，然后在其上沉积Ag。发现Ag颗粒在石墨烯区域上的形貌和分布与石墨烯厚度无关。Ag颗粒在外延石墨烯中诱导表面增强拉曼散射(SERS)效应和掺杂效应。随着石墨烯厚度的增加，SERS的增强因子以及G带的分裂和2D带的位移减小，这可归因于Ag与外延石墨烯之间相互作用的减弱。这通过第一性原理计算预测的Ag原子与6H-SiC上的外延石墨烯之间的电荷转移得到证实。这些结果有助于基于石墨烯的复合材料和器件的设计与开发。
