Tailoring manganese oxide with atomic precision to increase surface site availability for oxygen reduction catalysis.

Eom, C John; Kuo, Ding-Yuan; Adamo, Carolina; Moon, Eun Ju; May, Steve J; Crumlin, Ethan J; Schlom, Darrell G; Suntivich, Jin · Nat Commun · 2018

basic_science · Level V

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Abstract

Controlling the structure of catalysts at the atomic level provides an opportunity to establish detailed understanding of the catalytic form-to-function and realize new, non-equilibrium catalytic structures. Here, advanced thin-film deposition is used to control the atomic structure of La<sub>2/3</sub>Sr<sub>1/3</sub>MnO<sub>3</sub>, a well-known catalyst for the oxygen reduction reaction. The surface and sub-surface is customized, whereas the overall composition and d-electron configuration of the oxide is kept constant. Although the addition of SrMnO<sub>3</sub> benefits the oxygen reduction reaction via electronic structure and conductivity improvements, SrMnO<sub>3</sub> can react with ambient air to reduce the surface site availability. Placing SrMnO<sub>3</sub> in the sub-surface underneath a LaMnO<sub>3</sub> overlayer allows the catalyst to maintain the surface site availability while benefiting from improved electronic effects. The results show the promise of advanced thin-film deposition for realizing atomically precise catalysts, in which the surface and sub-surface structure and stoichiometry are tailored for functionality, over controlling only bulk compositions.