In Situ Studies of the Temperature-Dependent Surface Structure and Chemistry of Single-Crystalline (001)-Oriented La0.8Sr0.2CoO3-δ Perovskite Thin Films.
Perovskites are used to promote the kinetics of oxygen electrocatalysis in solid oxide fuel cells and oxygen permeation membranes. Little is known about the surface structure and chemistry of perovskites at high temperatures and partial oxygen pressures. Combining in situ X-ray reflectivity (XRR) and in situ ambient pressure X-ray photoelectron spectroscopy (APXPS), we report, for the first time, the evolution of the surface structure and chemistry of (001)-oriented perovskite La0.8Sr0.2CoO3-δ (LSC113) and (La0.5Sr0.5)2CoO4+δ (LSC214)-decorated LSC113 (LSC113/214) thin films as a function of temperature. Heating the (001)-oriented LSC113 surface leads to the formation of surface LSC214-like particles, which is further confirmed by ex situ Auger electron spectroscopy (AES). In contrast, the LSC113/214 surface, with activities much higher than that of LSC113, is stable upon heating. Combined in situ XRR and APXPS measurements support that Sr enrichment may occur at the LSC113 and LSC214 interface, which can be responsible for its markedly enhanced activities.
Zhenxing
Z
Feng
Ethan J
EJ
Crumlin
Wesley T
WT
Hong
Dongkyu
D
Lee
∇BASF SE, Carl-Bosch-Strasse 3, 67056 Ludwigshafen, Germany.
Eva
E
Mutoro
∥Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
Michael D
MD
Biegalski
◆Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States.
Hua
H
Zhou
Hendrik
H
Bluhm
∥Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
Hans M
HM
Christen
Yang
Y
Shao-Horn
electrocatalysis; fuel cell; oxygen reduction; perovskite oxides; strontium enrichment; surface and interface