Graphene edges and their electronic structures
Toshiaki Enoki
Department of Chemistry, Tokyo Institute of Technology

The electronic structure of graphene is affected seriously by the presence of edges depending on edge geometry, when a graphene sheet is cut into fragments. A nonbonding edge state of ?-electron origin is created in a zigzag-shaped edge. This is explained as broken symmetry of the pseudo-spin of massless Dirac fermion at the zigzag edge. Chemists can understand this as the degradation of aromaticity due to zigzag geometry. An electron scattering at an armchair edge is subjected to the interference, which takes place as the K-K’ inter-valley transition. In chemistry language, this corresponds to the presence of a unique Clar’s representation in armchair-edged molecules. We investigated the electronic structures of edge states using STM/STS and NEXAFS experiments in the zigzag edges. The electron wave interference effect in armchair edges has been investigated from the Raman G-band and STM supserlattice patterns. We successfully fabricated graphene nanostructures such as graphene nanoribbons using AFM technique.

Electronic structure analysis of novel carbon materials using synchrotron radiation
Masaharu Oshima
School of Engineering, The University of Tokyo

Novel carbon materials such as graphene and carbon catalysts have attracted much attention because of their unique electronic properties. In this talk, band structure analysis of graphene with different bandgap using angle-resolved photoelectron spectroscopy (ARPES) will be introduced together with new application of ARPES to quantum confinement of strongly correlated electron systems. Then, lateral interface analysis of graphene FET showing p-type conversion using a newly-developed 70 nm ARPES system at the SPring-8 UT beamline will be presented as the second topic. The third topic is carbon alloy catalysts (CAC) which are regarded as a promising candidate for polymer electrolyte fuel cell (PEFC) no-platinum cathode catalysts. In this talk, chemical structure analysis of impurity nitrogen atoms in CAC by photoelectron spectroscopy, edge state analysis of carbon nano-structured CAC by X-ray absorption spectroscopy, oxygen adsorption behaviors on impurity iron atoms in CAC by a newly-developed emission spectroscopy with 50 meV resolution will be discussed. This emission spectroscopy system at SPring-8 is used also for “operando” analysis of PEFC and Li ion battery.

From lithium ion battery to lithium air battery
Haoshen ZHOU
National Institute of Advanced Industrial Science and Technology

One of the key technologies for “low carbon society” is to develop clean energy device with both high power density and high energy density. Recently, many clean energy devices, such as lithium ion batteries, based on novel active materials have been investigated to improve the performance. I will introduce some works of lithium ion battery based on active materials related with carbon materials in my research group. However, even the largest energy density of lithium ion battery can’t satisfy the industrial needs resulted from the electric vehicle. Now, the lithium air battery with theoretic largest energy density has attracted much more attention. I will also introduce the lithium air battery based on metal free graphene as catalyst in the air electrode and other new type batteries developed in our research group.