Highly active postspinel-structured catalysts for oxygen evolution reaction
2022
Okazaki, Yuichi | Oda, Seiji | Takamatsu, Akihiko | Kawaguchi, Shogo | Tsukasaki, Hirofumi | Mori, Shigeo | Yagi, Shunsuke | Ikeno, Hidekazu | Yamada, Ikuya
The rational design principle of highly active catalysts for the oxygen evolution reaction (OER) is desired because of its versatility for energy-conversion applications. Postspinel-structured oxides, CaB₂O₄ (B = Cr³⁺, Mn³⁺, and Fe³⁺), have exhibited higher OER activities than nominally isoelectronic conventional counterparts of perovskite oxides LaBO₃ and spinel oxides ZnB₂O₄. Electrochemical impedance spectroscopy reveals that the higher OER activities for CaB₂O₄ series are attributed to the lower charge-transfer resistances. A density-functional-theory calculation proposes a novel mechanism associated with lattice oxygen pairing with adsorbed oxygen, demonstrating the lowest theoretical OER overpotential than other mechanisms examined in this study. This finding proposes a structure-driven design of electrocatalysts associated with a novel OER mechanism.
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