Molecular science of graphene nanostructures
Prof. Toshiaki Enoki, PhD
Tokyo Institute of Technology, Japan
Monday, October 17, 2016. 12:15 pm
Assembly hall of Faculty of Science, 17. listopadu 12, Olomouc
After the successful isolation of graphene (one-atom thick graphite) in 2004, graphene has become one of the central issues in nanoscience and nanotechnology. Among graphene derivatives, graphene nanostructure such as graphene nanoribbons, which can be obtained by cutting a graphene sheet in nano dimension, is one of the most exciting research targets, and it bridges between physics of graphene and chemistry of polycyclic aromatic hydrocarbon molecules, the former and the latter of which are based on relativistic quantum mechanics of massless Dirac fermion and aromatic sextet rule, respectively. And it differs essentially from fullerenes and carbon nanotubes belonging to the same family of carbon-based nanomaterials, as the former has open edges whereas the latter does not. Here the open edge plays an important role in its properties. When we cut a graphene sheet, there are two fundamental directions; armchair and zigzag directions. By cutting a graphene sheet and terminating the edge carbon atoms by foreign chemical species, we can create armchair and zigzag edges. Armchair-edged nanographenes are energetically stable due to the electron wave interference or aromatic stability, while zigzag-edged ones are unstable owing to the presence of nonbonding edge state localized in the vicinity of edges. The edge state is the important origin of various functionalities of graphene-based nanostructures. Physical and chemical properties will be discussed for graphene nanostructures.