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
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.