Fast Surface Oxygen Release Kinetics Accelerate Nanoparticle Exsolution in Perovskite Oxides

Area of Science:

• Materials Science
• Catalysis
• Surface Science

Background:

• Exsolution enables fabricating oxide-supported metal nanoparticle catalysts through phase precipitation.
• Understanding exsolution kinetics is crucial for optimizing catalysts for clean energy and fuel conversion.
• Oxygen release via oxygen vacancy formation is fundamental to oxide reduction and metal exsolution.

Purpose of the Study:

• To investigate the kinetics of metal nanoparticle exsolution from a host oxide.
• To determine the relationship between oxygen release kinetics and metal exsolution rates.
• To establish a predictive capability for tailoring exsolution processes.

Main Methods:

• Utilized thin-film perovskite SrTi$_{0.65}$Fe$_{0.35}$O$_{3}$ (STF) as a model system.
• Employed both experimental and theoretical approaches to probe surface exsolution kinetics.
• Performed in situ experiments and analytical kinetic modeling.

Main Results:

• Demonstrated that surface oxygen release kinetics govern metal nanoparticle exsolution in the STF system.
• Showed that increasing oxygen release rate (e.g., by reducing sample thickness or enhancing surface reactivity) accelerates Fe$^{0}$ exsolution.
• Observed that faster oxygen release shortened prereduction time and increased the quantity of exsolved Fe$^{0}$.

Conclusions:

• Surface oxygen release kinetics are the primary determinant of metal nanoparticle exsolution.
• Engineering host oxide surface oxygen release kinetics is vital for designing effective exsolved nanocatalysts.
• The study provides a predictive framework for optimizing exsolution processes for catalytic applications.