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Title: Surface Defect Chemistry and Electronic Structure of Pr 0.1Ce 0.9O 2-δ Revealed in Operando

Abstract

Understanding the surface defect chemistry of oxides under functional operating conditions is important for providing guidelines for improving the kinetics of electrochemical reactions. Ceria-based oxides have applications in solid oxide fuel/electrolysis cells, thermo-chemical water splitting, catalytic convertors, and red-ox active memristive devices. The surface defect chemistry of doped ceria in the regime of high oxygen pressure, pO 2, approximating the operating conditions of fuel cell cathodes at elevated temperatures, has not yet been revealed. In this paper, we investigated the Pr 0.1Ce 0.9O 2-δ (PCO) surface by in operando X-ray photoelectron and absorption spectroscopic methods. We quantified the concentration of reduced Pr 3+, at the near-surface region of PCO as a function of electrochemical potential, corresponding to a wide range of effective pO 2. We found that the Pr 3+ concentration at the surface was significantly higher than the values predicted from bulk defect chemistry. This finding indicates a lower effective defect formation energy at the surface region compared with that in the bulk. Finally, in addition, the Pr 3+ concentration has a weaker dependence on pO 2 compared to that in the bulk.

Authors:
ORCiD logo [1];  [2];  [2];  [1]; ORCiD logo [3];  [4];  [5]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Lab. for Electrochemical Interfaces. Dept. of Materials Science and Engineering
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Lab. for Electrochemical Interfaces. Dept. of Nuclear Science and Engineering
  3. Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II
  4. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Materials Science and Engineering
  5. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Lab. for Electrochemical Interfaces. Dept. of Materials Science and Engineering. Dept. of Nuclear Science and Engineering
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1460703
Report Number(s):
BNL-207841-2018-JAAM
Journal ID: ISSN 0897-4756
Grant/Contract Number:  
SC0012704; DMR-1419807
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 30; Journal Issue: 8; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Lu, Qiyang, Vardar, Gulin, Jansen, Maximilian, Bishop, Sean R., Waluyo, Iradwikanari, Tuller, Harry L., and Yildiz, Bilge. Surface Defect Chemistry and Electronic Structure of Pr0.1Ce0.9O2-δ Revealed in Operando. United States: N. p., 2018. Web. doi:10.1021/acs.chemmater.7b05129.
Lu, Qiyang, Vardar, Gulin, Jansen, Maximilian, Bishop, Sean R., Waluyo, Iradwikanari, Tuller, Harry L., & Yildiz, Bilge. Surface Defect Chemistry and Electronic Structure of Pr0.1Ce0.9O2-δ Revealed in Operando. United States. doi:10.1021/acs.chemmater.7b05129.
Lu, Qiyang, Vardar, Gulin, Jansen, Maximilian, Bishop, Sean R., Waluyo, Iradwikanari, Tuller, Harry L., and Yildiz, Bilge. Tue . "Surface Defect Chemistry and Electronic Structure of Pr0.1Ce0.9O2-δ Revealed in Operando". United States. doi:10.1021/acs.chemmater.7b05129. https://www.osti.gov/servlets/purl/1460703.
@article{osti_1460703,
title = {Surface Defect Chemistry and Electronic Structure of Pr0.1Ce0.9O2-δ Revealed in Operando},
author = {Lu, Qiyang and Vardar, Gulin and Jansen, Maximilian and Bishop, Sean R. and Waluyo, Iradwikanari and Tuller, Harry L. and Yildiz, Bilge},
abstractNote = {Understanding the surface defect chemistry of oxides under functional operating conditions is important for providing guidelines for improving the kinetics of electrochemical reactions. Ceria-based oxides have applications in solid oxide fuel/electrolysis cells, thermo-chemical water splitting, catalytic convertors, and red-ox active memristive devices. The surface defect chemistry of doped ceria in the regime of high oxygen pressure, pO2, approximating the operating conditions of fuel cell cathodes at elevated temperatures, has not yet been revealed. In this paper, we investigated the Pr0.1Ce0.9O2-δ (PCO) surface by in operando X-ray photoelectron and absorption spectroscopic methods. We quantified the concentration of reduced Pr3+, at the near-surface region of PCO as a function of electrochemical potential, corresponding to a wide range of effective pO2. We found that the Pr3+ concentration at the surface was significantly higher than the values predicted from bulk defect chemistry. This finding indicates a lower effective defect formation energy at the surface region compared with that in the bulk. Finally, in addition, the Pr3+ concentration has a weaker dependence on pO2 compared to that in the bulk.},
doi = {10.1021/acs.chemmater.7b05129},
journal = {Chemistry of Materials},
issn = {0897-4756},
number = 8,
volume = 30,
place = {United States},
year = {2018},
month = {3}
}

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