Strontium influence on the oxygen electrocatalysis of La2−xSrxNiO4±δ (0.0 ≤ xSr ≤ 1.0) thin films

Dongkyu Lee, Yueh-Lin Lee, Alexis Grimaud, Wesley T. Hong, Michael D. Biegalski, Dane Morgan, Yang Shao-Horn

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29 Scopus citations

Abstract

Substitution of lanthanum by strontium (Sr) in the A-site of cobalt-containing perovskites can greatly promote oxygen surface exchange kinetics at elevated temperatures. Little is known about the effect of A-site substitution on the oxygen electrocatalysis of Ruddlesden-Popper (RP) oxides. In this study, we report, for the first time, the growth and oxygen surface exchange kinetics of La2-xSrxNiO 4±δ (LSNO, 0.0 ≤ xSr ≤ 1.0) thin films grown on (001)cubic-Y2O3-stabilized ZrO 2 (YSZ) by pulsed laser deposition. High-resolution X-ray diffraction analysis revealed that the LSNO film orientation was changed gradually from the (100)tetra. (in-plane) to the (001)tetra. (out-of-plane) orientation in the RP structure with increasing Sr from La2NiO 4+δ (xSr = 0) to LaSrNiO4±δ (xSr = 1.0). Such a change in the LSNO film orientation was accompanied by reduction in the oxygen surface exchange kinetics by two orders of magnitude as shown from electrochemical impedance spectroscopy results. Density functional theory (DFT) calculations showed that Sr substitution could stabilize the (001)tetra. surface relative to the (100) tetra. surface and both Sr substitution and increasing (001) tetra. surface could greatly weaken adsorption of molecular oxygen in the La-La bridge sites in the RP structure, which can reduce oxygen surface exchange kinetics. This journal is © the Partner Organisations 2014.
Original languageEnglish (US)
Pages (from-to)6480-6487
Number of pages8
JournalJournal of Materials Chemistry A
Volume2
Issue number18
DOIs
StatePublished - 2014
Externally publishedYes

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