著者

Ikuya Yamada Atsushi Tanaka Seiji Oda Yuichi Okazaki Fumito Toda Yuta Kato Yuta Kizawa Masaya Oshita Manami Goto Amane Morimura Asuka Ochi Kaoru Toda Wencong Wang Hajime Yamamoto Hidekazu Ikeno Shunsuke Yagi

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.64, no.9, pp.2097-2104, 2023-09-01 (Released:2023-08-25)

参考文献数

37

---

Chemical substitution is an effective way to improve electrocatalytic properties in transition metal oxides. We investigate the synergistic effect between Fe4+ and Co4+ ions on the catalytic activity for oxygen evolution reaction (OER) in the Fe–Co-mixed perovskite oxide CaFe1−xCoxO3. The OER activity of CaFe1−xCoxO3 is substantially increased by small amounts of Co (Fe) doping into CaFeO3 (CaCoO3), leading to the superiority compared to the pure Fe and Co perovskite oxides. The x dependences of the OER overpotential and specific activity for CaFe1−xCoxO3 (0.05 ≦ x ≦ 0.95) are expressed by constant offset from the weighted average between CaFeO3 and CaCoO3, which can be interpreted to be the synergistic effect between Fe4+ and Co4+ ions on OER activity. The absence of the optimum x for the highest activity for CaFe1−xCoxO3 contrasts with the volcano-like plots reported in various mixed-metal oxides. First-principle calculations using the special quasirandom structure models on CaFe1−xCoxO3 (x = 0.03–0.5) demonstrate that about half the amount of Fe4+ is electronically activated to possess smaller charge-transfer energies, corroborating the enhancement of catalytic activity in CaFe1−xCoxO3. These findings provide new insight into the synergistic effects in complex transition metal oxide catalysts.

著者

山本 孟 Hajime Yamamoto

出版者

同志社大学一神教学際研究センター(CISMOR)

雑誌

一神教世界 = The world of monotheistic religions (ISSN:21850380)

巻号頁・発行日

no.11, pp.1-15, 2020-03-31

---

ヒッタイト王国は前2千年紀のアナトリア中央を中心に栄えた王国である。前13世紀のヒッタイト王ハットゥシリ3世が作成した『ハットゥシリ3世の弁明』という文書には、王と王妃プドゥヘパの「愛」について述べられる箇所がある。本稿では、この文書において王と王妃の愛が語られる理由を、ヒッタイト語で「愛」と訳される語の用例から考察する。愛にかんする語の用例には、男女の関係としての「愛」と支配者の関係としての「愛」がある。このことを踏まえると、ハットゥシリとプドゥヘパの「愛のある関係」とは、イシュタル神の力で異性として惹かれ合い、夫婦として調和のとれた様子を意味したと理解される。加えて、政治的文脈で使用される用例からは、支配者たちが契約関係を結ぶための法的根拠となる術語であったこともわかる。したがって、『ハットゥシリ3世の弁明』にみられる「愛」とは、愛情をもった夫婦であることを示すと同時に、ハットゥシリ3世が政治的なパートナーとしてプドゥヘパの高い地位を法的に認めるために言及したものと考えられる。The Hittite text known as the Apology of Ḫattušili III (CTH 81) mentions "love" between the king Ḫattušili III and his queen Puduḫepa. This paper reveals the reason their "love" was narrated in the text from an analysis of the usage of Hittite words that indicate "love." Their love, which was granted by the goddess Ištar/Šauška, shows how they were attracted to each other, and in harmony, became husband and wife. In the political context, love between rulers was cited as legal act, therefore in Ḫattušili III and Puduḫepa case, it justifies the couple's binding in a political partnership. Thus, with the inclusion of episodes describing their love, Ḫattušili III might had intended to show the legal recognition of Puduḫepa's high status in the Hittite royal family being almost equal to that of her husband as well as to show that their affection was indeed granted by Ištar.