Surface reduction properties of ceria-zirconia solid solutions: a first-principles study.
Xuesong Cao1, Chenxi Zhang1, Zehua Wang1
1Environment Research Institute, Shandong University Qingdao 266200 P. R. China caoxueshine@163.com sdzhangcx@163.com zhstart13@foxmail.com lwen951014@163.com sxmwch@sdu.edu.cn.
RSC Advances
|May 2, 2022
Summary
Density functional theory revealed that cerium zirconium oxide (Ce1-xZrxO2) surfaces show optimal catalytic activity for CO oxidation. The Ce0.875Zr0.125O2 composition demonstrated the lowest activation energy, indicating superior performance.
Area of Science:
- Materials Science
- Surface Chemistry
- Computational Chemistry
Background:
- Ceria-based materials are crucial for catalytic applications.
- Understanding the surface reduction properties of mixed cerium-zirconium oxides (Ce1-xZrxO2) is essential for optimizing their catalytic performance.
- The (110) surface plane is often a key active site in ceria-based catalysts.
Purpose of the Study:
- To systematically investigate the reduction properties of Ce1-xZrxO2 (110) surfaces across the entire composition range using density functional theory (DFT).
- To identify the specific composition exhibiting the most promising catalytic effectiveness for CO oxidation.
- To elucidate the relationship between surface composition, oxygen vacancy formation, and catalytic activity.
Main Methods:
- Density functional theory (DFT) calculations were employed to study the thermodynamic properties of Ce1-xZrxO2 (110) surfaces.
- A large supercell approach was used to model the complete range of compositions (x = 0.125 to 0.875).
- Carbon monoxide (CO) was used as a probe molecule to calculate energy barriers for CO oxidation by lattice oxygen.
Main Results:
- The composition Ce0.875Zr0.125O2 exhibited the most effective catalytic activity, characterized by the lowest activation energy barrier (0.899 eV) for CO oxidation.
- Surface oxygen ions (O3c) coordinated with two Zr and one Ce ion were more easily released than those coordinated with two Ce and one Zr ion.
- Differences in oxygen release were attributed to the varying binding strengths of oxygen with different neighboring cations (Ce and Zr).
Conclusions:
- The Ce0.875Zr0.125O2 (110) surface demonstrates superior catalytic performance for CO oxidation due to facile oxygen release.
- The local coordination environment of surface oxygen ions significantly influences their mobility and reactivity.
- DFT calculations provide valuable insights into the structure-activity relationships of mixed ceria-zirconia catalysts.
