skip to main content

Title: Oxygen surface exchange kinetics and stability of (La,Sr) 2 CoO 4±δ/La 1-xSr xMO 3-δ (M = Co and Fe) hetero-interfaces at intermediate temperatures

Heterostructured oxide interfaces created by decorating Ruddlesden-Popper phases (A2BO4) or perovskites on perovskites have shown not only pronounced cation segregation at the interface and in the A2BO4 structure but also much enhanced kinetics for oxygen electrocatalysis at elevated temperatures. In this study, we report and compare the time-dependent surface exchange kinetics and stability of (La 0.5Sr 0.5) 2CoO 4 -decorated (LSC 214) La 0.6Sr 0.4Co 0.2Fe 0.8O 3-δ (LSCF 113) and La 0.8Sr 0.2CoO 3-δ (LSC 113) thin films. While LSC 214 decoration on LSC 113 greatly reduced the degradation in the surface exchange kinetics as a function of time relative to LSC 113, LSCF 113 with LSC 214 coverage showed comparable surface exchange kinetics and stability to LSCF 113. This difference can be explained by greater surface stability of LSCF 113 than LSC 113 under testing conditions, and that LSC 214 decoration on LSC 113 reduced the decomposition of LSC 113 to form secondary phases that impedes oxygen exchange kinetics, and thus resulted in enhanced stability. This hypothesis is supported by the observations that annealing at 550 °C led to the formation of Sr-rich secondary particles on LSC 113 while no such particles were observed on LSCF 113. Densitymore » functional theory (DFT) computation provides further support, which revealed greater capacity of surface Sr segregation for LSCF 113 having SrO termination than LSC 113 having (La 0.25Sr 0.75)O termination for the experimental conditions, and lower energy gain to move Sr from LSCF 113 into LSC 214 relative to the LSC 214-LSC 113 system.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Electrochemical Energy Lab. and Dept. of Mechanical Engineering
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Electrochemical Energy Lab. and Dept. of Materials Science and Engineering
  3. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
  4. Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering
  5. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Electrochemical Energy Lab., Dept. of Mechanical Engineering, and Dept. of Materials Science and Engineering
Publication Date:
OSTI Identifier:
1185681
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Materials Chemistry. A
Additional Journal Information:
Journal Volume: 3; Journal Issue: 5; Journal ID: ISSN 2050-7488
Publisher:
Royal Society of Chemistry
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; LSCO fuel cell anode XPS