Research Theme of Moritomo lab.
Science of Energy & Environ. Material 

1.     Prussian blue analogue as cathode material of Sodium-ion battery: We found that thin film of Prussian blue analogue exhibits a high capacity and high discharge rate in a sodium-ion battery (SIB) cell. In order to use this material, we have to develop a technique to make fine powders with conducting coting.[ For example, M. Takachi, T. Matsuda, and Y. Moritomo, "Cobalt Hexacyanoferrate as Cathode Material for Na+ Secondary Battery", Appl. Phys. Express 6, 025802 (2013). T. Matsuda, M. Takachi and Y. Moritomo,"A sodium manganese ferrocyanide thin film for Na-ion batteries", Chem. Comm. 49, 2721 (2013). ]

2.     Unified picture of layered transition metal oxides NaxMO2: Layered transition metal oxides NaxMO2 is promising cathode material of SIB. But, basic physical properties, such as structure and electronic state against Na-ion concentration, were not clarified. Now, we are systematically performing in situ X-ray diffraction and X-ray absorption spectroscopy. We try to combine these experimental data with ab initio calculation, which will clarify the physics of the Na interaction. We believe that this type of basic scientific investigation will contribute the safety of the SIB and the logical development of SIB.[ For example, T. Shinomo, D. Tanabe, W. Kobayashi, and Y. Moritomo, “Structural response of P2-type NaxMnO2 against Li+ intercalation”, J. Phys. Soc. Jpn. 82, 083601 (2013).T. Shinomo, D. Tanabe, W. Kobayashi, and Y. Moritomo, “Electronic state of P2-type NaxMO2 (M = Co nad Mn) as investigated by in situ X-ray absorption spectroscopy.”, J. Phys. Soc. Jpn. 82, 124727 (2013).]

3.     Charge dissociation mechanism of organic photovoltaic: The organic photovoltaic (OPV) is a promising energy convertor with low-cost, and flexible, and environment-friendly. Recently, the power conversion efficiently (PCE) of the device exceeds 10%. However, the mechanism of the charge dissociation from exciton is remains unclear. Note that the exciton binding energy (several hundred meV) is high as compared with the room temperature. By means of the ultrafast spectroscopy, we try to reveal the mechanism.[ For example, K. Yonezawa, H. Kamioka, T. Yasuda, L. Han, and Y. Moritomo, “Robust carrier formation process in low-band gap organic photovoltaic”, Appl. Phys. Lett., 103 (2013)173901. K. Yonezawa, M. Ito, H. Kamioka, T. Yasuda, L. Han, and Y. Moritomo, “Fast carrier formation from acceptor exciton in low-gap organic photovoltaic”, Appl. Phys. Express, 5, 042302 (2012).]

4.     Soft-X-ray microscopic investigation on OPV: Unfortunately, the donor-acceptor interface of OPV is remains unclear. These were few report on this problem. We started a soft-X-ray microscopic investigation on donor-acceptor interface structure in nm scale, i collaboration with the photon factory (PF) of KEK, Japan. We further clarify the interface structure and PCE.

5   Decontamination of radioactive Cs+: We found that Prussian blue analogue exhibits a high performance of decontamination of radioactive Cs+ from aqueous solution. A single precipitation procedure reduced the radioactivity more than 3 order. We want to expand this investigation to Sr2+.[ For example, A. Omura and Y. Moritomo,“Cs+ trapping in size-controlled nanospaces of hexacyanoferrates”, Appl. Phys. Express 5, 057101 (2012).]