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Tuning Oxide Properties by Oxygen Vacancy Control During Growth and Annealing
Published on: June 9, 2023
Oxygen vacancy formation in CeO2 and Ce(1-x)Zr(x)O2 solid solutions: electron localization, electrostatic potential
Hai-Feng Wang1, Hui-Ying Li, Xue-Qing Gong
1Labs for Advanced Materials, Research Institute of Industrial Catalysis, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, PR China.
Physical Chemistry Chemical Physics : PCCP
|October 20, 2012
Summary
Ceria-based materials exhibit excellent oxygen storage capacity due to oxygen vacancies. This study explores doping effects and structural relaxations, crucial for tuning this property in advanced catalytic applications.
Area of Science:
- Materials Science
- Catalysis
- Computational Chemistry
Background:
- Ceria (CeO2) and ceria-based composites like Ce(1-x)Zr(x)O2 are vital for catalytic processes, e.g., three-way catalysts, due to their oxygen storage capacity (OSC).
- Understanding oxygen vacancy formation and its tuning via doping is central to ceria material chemistry, yet electronic structure calculations in defective oxides present challenges.
- The DFT + U technique is a pragmatic approach widely used for theoretical investigations of these materials.
Purpose of the Study:
- To review electronic structure calculations of defective CeO2(111), focusing on 4f electron configurations and oxygen vacancy formation mechanisms.
- To summarize theoretical results on the doping effect in Ce(1-x)Zr(x)O2 solid solutions, examining dopant concentrations and crystal phases.
- To discuss the role of structural relaxation and electrostatic fields in oxygen vacancy formation in ceria-based materials and nanoparticles.
Main Methods:
- Review of recent theoretical investigations using Density Functional Theory (DFT) with on-site Coulomb correction (DFT + U).
- Analysis of electronic structures, defect configurations, and relaxation patterns in defective ceria and ceria-zirconia solid solutions.
- Comparison of oxygen vacancy formation in bulk, surfaces, and nanoparticles of ceria.
Main Results:
- Multiple configurations of localized 4f electrons in defective CeO2(111) influence oxygen vacancy formation and O2 activation.
- Doping in Ce(1-x)Zr(x)O2 solid solutions tunes oxygen vacancy formation, with localized structural relaxation playing a key role in OSC, especially in kappa-phase.
- Electrostatic fields significantly influence oxygen vacancy formation in ceria nanoparticles, differing from bulk or surface behavior.
Conclusions:
- Localized structural relaxation is a critical factor in achieving high oxygen storage capacity in ceria-based materials.
- The DFT + U method provides valuable insights into the electronic and structural properties governing oxygen vacancy formation.
- Understanding these factors is essential for designing advanced ceria-based catalysts with enhanced performance.
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