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Nakamura, Shota*; Hyodo, Kazushi*; Matsumoto, Yuji*; Haga, Yoshinori; Sato, Hitoshi*; Ueda, Shigenori*; Mimura, Kojiro*; Saiki, Katsuyoshi*; Iso, Kosei*; Yamashita, Minoru*; et al.
Journal of the Physical Society of Japan, 89(2), p.024705_1 - 024705_5, 2020/02
Times Cited Count:2 Percentile:19.17(Physics, Multidisciplinary)Sumida, Kazuki*; Shirai, Kaito*; Zhu, S.-Y.*; Taniguchi, Masaki*; Ye, M.*; Ueda, Shigenori*; Takeda, Yukiharu; Saito, Yuji; Aseguinolaza, I. R.*; Barandiarn, J. M.*; et al.
Physical Review B, 91(13), p.134417_1 - 134417_6, 2015/04
Times Cited Count:6 Percentile:26.77(Materials Science, Multidisciplinary)Kobayashi, Masaki*; Niwa, Hideharu*; Harada, Yoshihisa*; Horiba, Koji*; Oshima, Masaharu*; Ofuchi, Hironori*; Terakura, Kiyoyuki*; Ikeda, Takashi; Koshigoe, Yuka*; Ozaki, Junichi*; et al.
Journal of Power Sources, 196(20), p.8346 - 8351, 2011/10
Times Cited Count:32 Percentile:66.17(Chemistry, Physical)The electronic structure of Co atoms in CoPc-based carbon catalysts, which were prepared by pyrolyzing a mixture of CoPc and phenol resin polymer up to 1000C, has been investigated using XAFS analysis and HXPES. The Co K XAFS spectra show that most of the Co atoms are in the metallic state and small quantities of oxidized Co components are present in the samples even after acid washing to remove Co atoms. Based on the difference in probing depth between XAFS and HXPES, it was found that after acid washing, the surface region with the aggregated Co clusters is primarily composed of metallic Co. Since the electrochemical properties remain almost unchanged even after the acid washing process, the residual metallic and oxidized Co atoms themselves will hardly contribute to the ORR activity of the CoPc-based carbon cathode catalysts, implying that the active sites of the CoPc-based catalysts primarily consist of light elements such as C and N.
Utsumi, Yuki*; Sato, Hitoshi*; Kurihara, Hidenao*; Maso, Hiroyuki*; Hiraoka, Koichi*; Kojima, Kenichi*; Tobimatsu, Komei*; Okochi, Takuo*; Fujimori, Shinichi; Takeda, Yukiharu; et al.
Physical Review B, 84(11), p.115143_1 - 115143_7, 2011/09
Times Cited Count:13 Percentile:45.83(Materials Science, Multidisciplinary)We have studied conduction-band (CB) electronic states of a typical valence-transition compound YbInCu by means of temperature-dependent hard X-ray photoemission spectroscopy (HX-PES), soft X-ray absorption spectroscopy (XAS), and soft X-ray photoemission spectroscopy (SX-PES) of the valence band. We have described the valence transition in YbInCu in terms of the charge transfer from the CB to Yb 4 states.
Niwa, Hideharu*; Kobayashi, Masaki*; Horiba, Koji*; Harada, Yoshihisa*; Oshima, Masaharu*; Terakura, Kiyoyuki*; Ikeda, Takashi; Koshigoe, Yuka*; Ozaki, Junichi*; Miyata, Seizo*; et al.
Journal of Power Sources, 196(3), p.1006 - 1011, 2011/02
Times Cited Count:92 Percentile:91.12(Chemistry, Physical)We report on the electronic structure of three different types of N-containing carbon-based cathode catalysts for polymer electrolyte fuel cells observed by hard X-ray photoemission spectroscopy. C 1s spectra show the importance of carbon network formation for the oxygen reduction reaction (ORR) activity. Samples having high oxygen reduction reaction activity in terms of oxygen reduction potential contain high concentration of graphite-like nitrogen. Based on a quantitative analysis of our results, the oxygen reduction reaction activity of the carbon-based cathode catalysts will be improved by increasing concentration of graphite-like nitrogen in a developed carbon network.
Saito, Yuji; Kimura, Hiroaki*; Suzuki, Yoshio*; Nakatani, Takeshi*; Matsushita, Tomohiro*; Muro, Takayuki*; Miyahara, Tsuneaki*; Fujisawa, M.*; Soda, Kazuo*; Ueda, Shigenori*; et al.
Nuclear Instruments and Methods in Physics Research A, 467-468(Part.1), p.553 - 556, 2001/07
Times Cited Count:23 Percentile:81.84(Instruments & Instrumentation)no abstracts in English
Ueda, Shigenori*; Imada, Shin*; Muro, Takayuki*; Saito, Yuji; Suga, Shigemasa*; Matsukura, F.*; Ohno, Hideo*
Physica E, 10(1-3), p.210 - 214, 2001/05
Times Cited Count:24 Percentile:73.43(Nanoscience & Nanotechnology)no abstracts in English
Saito, Yuji; Kimura, Hiroaki*; Suzuki, Yoshio*; Nakatani, Takeshi*; Matsushita, Tomohiro*; Muro, Takayuki*; Miyahara, Tsuneaki*; Fujisawa, M.*; Soda, Kazuo*; Ueda, Shigenori*; et al.
Review of Scientific Instruments, 71(9), p.3254 - 3259, 2000/09
Times Cited Count:187 Percentile:98.96(Instruments & Instrumentation)no abstracts in English
Fugane, Keisuke*; Mori, Toshiyuki*; Wu, Y. Y.*; Yamamoto, Shunya; Maekawa, Yasunari; Yoshikawa, Hideki*; Yamashita, Yoshiyuki*; Ueda, Shigenori*; Vladimir, M.*; Suzuki, Akira*; et al.
no journal, ,
no abstracts in English
Nakano, Kiho*; Nabetani, Koichiro*; Azuma, Masaki*; Oka, Kengo*; Mizumaki, Masaichiro*; Agui, Akane; Ueda, Shigenori*
no journal, ,
no abstracts in English