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Title: Oxygen vacancy formation characteristics in the bulk and across different surface terminations of La(1₋x)SrxFe(1₋y)CoyO(3₋δ) perovskite oxides for CO2 conversion

Density functional theory (DFT) based investigation of two parameters of prime interest -- oxygen vacancy and surface terminations along (100) and (110) planes -- has been conducted for La(1-x)SrxFe(1-y)CoyO(3-$$\delta$$) perovskite oxides in view of their application towards thermochemical carbon dioxide conversion reactions. The bulk oxygen vacancy formation energies for these mixed perovskite oxides are found to increase with increasing lanthanum and iron contents in the 'A' site and 'B' site, respectively. Surface terminations along (100) and (110) crystal planes are studied to probe their stability and their capabilities to accommodate surface oxygen vacancies. Amongst the various terminations, the oxygen-rich (110) surface and strontium-rich (100) surface are the most stable, while transition metal-rich terminations along (100) revealed preference towards the production of oxygen vacancies. The carbon dioxide adsorption strength, a key descriptor for CO2 conversion reactions, is found to increase on oxygen vacant surfaces thus establishing the importance of oxygen vacancies in CO2 conversion reactions. Amongst all the surface terminations, the lanthanum-oxygen terminated surface exhibited the strongest CO2 adsorption strength. Finally, the theoretical prediction of the oxygen vacancy trends and the stability of the samples were corroborated by the temperature-programmed reduction and oxidation reactions and in situ XRD crystallography.
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [1]
  1. Univ. of South Florida, Tampa, FL (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
OSTI Identifier:
1249404
Report Number(s):
NREL/JA-5100-66343
Journal ID: ISSN 2050-7488; JMCAET
Grant/Contract Number:
AC36-08GO28308; CBET-1335817; CHE-1531590
Type:
Accepted Manuscript
Journal Name:
Journal of Materials Chemistry. A
Additional Journal Information:
Journal Volume: 4; Journal Issue: 14; Journal ID: ISSN 2050-7488
Publisher:
Royal Society of Chemistry
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; density functional theory; oxygen vacancy; surface terminations; perovskite oxides; surface termination; CO2 conversion