Oxygen vacancy formation and migration in Ce(1-x)Zr(x)O2 catalyst: a DFT+U calculation

Area of Science:

• Materials Science
• Computational Chemistry
• Catalysis

Background:

• Ceria (CeO2) based materials are crucial for catalysis, particularly in oxygen storage applications.
• Understanding oxygen vacancy formation and migration is key to optimizing ceria's performance.
• Doping ceria with other elements, like zirconia (ZrO2), can significantly alter its properties.

Purpose of the Study:

• To investigate the effect of zirconium substitution on the oxygen vacancy and migration in Ce(1-x)Zr(x)O2.
• To correlate structural and electronic modifications with oxygen storage capacity (OCS).
• To identify the optimal Ce/Zr ratio for enhanced catalytic activity.

Main Methods:

• Spin-polarized density functional theory with on-site Coulomb correction (DFT+U) calculations.
• Analysis of oxygen vacancy formation energy (E(f)).
• Calculation of activation energy for oxygen vacancy migration.
• Detailed electronic structure analysis.

Main Results:

• Zirconium substitution in ceria creates activated oxygen, enhancing OCS.
• Oxygen vacancy formation energy (E(f)) decreases with increasing zirconia content.
• The Ce0.5Zr0.5O2 composition shows the lowest E(f) and superior OCS.
• Facile oxygen vacancy migration is observed, particularly in 50% Zr-doped ceria.

Conclusions:

• Zirconium doping effectively enhances the oxygen storage capacity of ceria.
• The optimal composition for improved OCS and oxygen mobility is Ce0.5Zr0.5O2.
• Electronic and structural modifications induced by Zr substitution are responsible for the enhanced catalytic properties.