Periodic structural changes in Pd nanoparticles during oscillatory CO oxidation reaction.

Area of Science:

• Materials Science
• Chemical Engineering
• Catalysis

Background:

• Nanoparticle (NP) catalysts are crucial for energy, chemical production, and environmental applications.
• Understanding NP surface dynamics under reaction conditions is vital for optimizing catalytic activity.
• Current knowledge lacks atomic-scale insights into NP surface reconstruction and its impact on catalysis.

Purpose of the Study:

• To investigate the atomic-scale surface restructuring of nanoparticle catalysts under reaction conditions.
• To elucidate the relationship between NP surface dynamics and catalytic activity during CO oxidation.
• To reveal the mechanism behind spontaneous oscillations in catalytic conversion.

Main Methods:

• Operando transmission electron microscopy (TEM) was employed to observe nanoparticle behavior in real-time.
• The study focused on Palladium (Pd) nanoparticles (NPs) during carbon monoxide (CO) oxidation.
• Experiments were conducted under atmospheric pressure and elevated temperatures.

Main Results:

• Palladium (Pd) NPs were observed to undergo periodic round-to-flat shape transitions, altering their facets.
• These dynamic structural changes led to spontaneous oscillations in the conversion of CO to CO2.
• The oscillations were attributed to CO-adsorption-mediated restructuring between high-index and low-index facets.

Conclusions:

• The dynamic restructuring of NP surfaces significantly impacts catalytic activity, leading to oscillatory behavior.
• CO adsorption plays a critical role in mediating these periodic surface reconstructions.
• Atomic-scale understanding of NP dynamics under reactive conditions is essential for designing high-performance catalysts.