jz400250t_si_001.pdf (3.17 MB)
In Situ Studies of the Temperature-Dependent Surface Structure and Chemistry of Single-Crystalline (001)-Oriented La0.8Sr0.2CoO3−δ Perovskite Thin Films
journal contribution
posted on 2015-12-16, 22:44 authored by Zhenxing Feng, Ethan
J. Crumlin, Wesley
T. Hong, Dongkyu Lee, Eva Mutoro, Michael D. Biegalski, Hua Zhou, Hendrik Bluhm, Hans M. Christen, Yang Shao-HornPerovskites 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.