Synthesis of Novel Melilite-Type Iron/Cobalt Oxides and Their Oxygen Evolution Reaction Electrocatalytic Activity
journal contributionposted on 08.07.2020, 19:34 by Satoshi Ogawa, Yasuyo Ogino, Masao Yonemura, Toshiharu Fukunaga, Hisao Kiuchi, Kei Nakayama, Ryo Ishikawa, Yuichi Ikuhara, Yoshihiro Doi, Kenta Suzuki, Miwa Saito, Teruki Motohashi
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Here, we report the synthesis and oxygen evolution reaction (OER) electrocatalytic activity of A2Fe2–2xCoxGe1+xO7 (A = Sr and Ba) with a melilite-type structure. The iron/cobalt-mixed melilites were successfully synthesized for the first time and found to exhibit high OER activity in highly alkaline media. In particular, the OER performance of Sr2Fe0.67Co0.67Ge1.66O7 (x = 0.67) is comparable to, or even superior to, that of a precious-metal catalyst, RuO2. The remarkable OER activity of the melilites seems to originate from a synergetic effect of Fe/Co coexistence as well as the structural feature of melilites, where “coordinatively unsaturated” Fe/Co sites effectively promote the formation of catalytically active surface layers through the adsorption of OH– ions in highly alkaline media.