MIT Libraries logoDSpace@MIT

MIT
View Item 
  • DSpace@MIT Home
  • MIT Open Access Articles
  • MIT Open Access Articles
  • View Item
  • DSpace@MIT Home
  • MIT Open Access Articles
  • MIT Open Access Articles
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

Impact of Sr segregation on the electronic structure and oxygen reduction activity of SrTi[subscript 1−x]Fe[subscript x]O[subscript 3] surfaces

Author(s)
Chen, Yan; Cai, Zhuhua; Kim, Jae Jin; Tuller, Harry L.; Yildiz, Bilge; Jung, Woo Chul; ... Show more Show less
Thumbnail
DownloadSTF Manuscript revised final 03262012 yildz.pdf (610.7Kb)
OPEN_ACCESS_POLICY

Open Access Policy

Creative Commons Attribution-Noncommercial-Share Alike

Terms of use
Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/
Metadata
Show full item record
Abstract
The correlation between the surface chemistry and electronic structure is studied for SrTi[subscript 1−x]Fe[subscript x]O[subscript 3] (STF), as a model perovskite system, to explain the impact of Sr segregation on the oxygen reduction activity of cathodes in solid oxide fuel cells. Dense thin films of SrTi[subscript 0.95]Fe[subscript 0.05]O[subscript 3] (STF5), SrTi[subscript 0.65]Fe[subscript 0.35]O[subscript 3] (STF35) and SrFeO[subscript 3] (STF100) were investigated using a coordinated combination of surface probes. Composition, chemical binding, and valence band structure analysis using angle-resolved X-ray photoelectron spectroscopy showed that Sr enrichment increases on the STF film surfaces with increasing Fe content. In situ scanning tunnelling microscopy/spectroscopy results proved the important and detrimental impact of this cation segregation on the surface electronic structure at high temperature and in an oxygen environment. While no apparent band gap was found on the STF5 surface due to defect states at 345 °C and 10[superscript −3] mbar of oxygen, the surface band gap increased with Fe content, 2.5 ± 0.5 eV for STF35 and 3.6 ± 0.6 eV for STF100, driven by a down-shift in energy of the valence band. This trend is opposite to the dependence of the bulk STF band gap on the Fe fraction, and is attributed to the formation of a Sr-rich surface phase in the form of SrO[subscript x] on the basis of the measured surface band structure. The results demonstrate that Sr segregation on STF can deteriorate oxygen reduction kinetics through two mechanisms – inhibition of electron transfer from bulk STF to oxygen species adsorbing onto the surface and the smaller concentration of oxygen vacancies available on the surface for incorporating oxygen into the lattice.
Date issued
2012-04
URI
http://hdl.handle.net/1721.1/86172
Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering; Massachusetts Institute of Technology. Department of Nuclear Science and Engineering; Massachusetts Institute of Technology. Laboratory for Electrochemical Interfaces
Journal
Energy & Environmental Science
Publisher
Royal Society of Chemistry
Citation
Chen, Yan, WooChul Jung, Zhuhua Cai, Jae Jin Kim, Harry L. Tuller, and Bilge Yildiz. “Impact of Sr Segregation on the Electronic Structure and Oxygen Reduction Activity of SrTi1−xFexO3 Surfaces.” Energy & Environmental Science 5, no. 7 (2012): 7979.
Version: Author's final manuscript
ISSN
1754-5692
1754-5706

Collections
  • MIT Open Access Articles

Browse

All of DSpaceCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

My Account

Login

Statistics

OA StatisticsStatistics by CountryStatistics by Department
MIT Libraries
PrivacyPermissionsAccessibilityContact us
MIT
Content created by the MIT Libraries, CC BY-NC unless otherwise noted. Notify us about copyright concerns.