Department of Chemistry, Columbia University , New York, New York 10027, United States.
J Am Chem Soc. 2014 Jan 29;136(4):1391-7. doi: 10.1021/ja408463g. Epub 2014 Jan 15.
Atomic-level details of dopant distributions can significantly influence the material properties. Using scanning tunneling microscopy, we investigate the distribution of substitutional dopants in nitrogen-doped graphene with regard to sublattice occupancy within the honeycomb structure. Samples prepared by chemical vapor deposition (CVD) using pyridine on copper exhibit well-segregated domains of nitrogen dopants in the same sublattice, extending beyond 100 nm. On the other hand, samples prepared by postsynthesis doping of pristine graphene exhibit a random distribution between sublattices. On the basis of theoretical calculations, we attribute the formation of sublattice domains to the preferential attachment of nitrogen to the edge sites of graphene during the CVD growth process. The breaking of sublattice symmetry in doped graphene can have important implications in its electronic applications, such as the opening of a tunable band gap in the material.
掺杂剂分布的原子级细节会显著影响材料的性能。我们利用扫描隧道显微镜研究了氮掺杂石墨烯中取代型掺杂剂在蜂窝状结构中占据亚晶格的分布情况。使用吡啶在铜上通过化学气相沉积（CVD）制备的样品，在 100nm 以上的范围内表现出氮掺杂剂在同一亚晶格中很好地分离的畴。另一方面，通过原始石墨烯的后合成掺杂制备的样品在亚晶格之间表现出随机分布。基于理论计算，我们认为亚晶格畴的形成归因于在 CVD 生长过程中氮优先附着在石墨烯的边缘位上。掺杂石墨烯中亚晶格对称性的破坏可能对其电子应用有重要影响，例如在材料中打开可调谐的带隙。
