Memory-dictated dynamics of single-atom Pt on CeO₂ for CO oxidation

Area of Science:

• Catalysis
• Materials Science
• Surface Chemistry

Background:

• Precious metals like platinum are crucial for automotive exhaust treatment catalysts.
• Reducing the amount of platinum required is economically and environmentally beneficial.
• Single-atom catalysis presents a promising strategy for maximizing metal utilization.

Purpose of the Study:

• To investigate the dynamic behavior of two distinct single-atom platinum structures on ceria (CeO2).
• To compare the catalytic activity and stability of these structures during carbon monoxide (CO) oxidation.
• To understand the influence of the initial single-atom configuration on catalyst performance and memory effects.

Main Methods:

• Fabrication of two types of single-atom platinum on ceria: adsorbed Pt1 in Pt/CeO2 (500°C) and square planar Pt1 in PtATCeO2 (atom-trapping at 800°C).
• In situ monitoring of catalyst behavior during CO oxidation.
• Analysis of catalyst structure and reactivity under different treatment conditions (reduction and reoxidation).

Main Results:

• Adsorbed Pt1 on CeO2 is mobile, forming clusters during CO oxidation, leading to high reactivity and near-zero CO reaction order.
• Square planar Pt1 on CeO2 is stable, exhibiting lower reactivity and a positive CO reaction order.
• Both Pt1 structures transform into platinum nanoparticles upon reduction in CO.
• Catalysts retain memory of their initial single-atom state after reoxidation, highlighting structural importance.

Conclusions:

• The dynamic evolution and anchoring of single-atom platinum on ceria significantly influence catalytic activity and reaction mechanisms.
• The initial structure of single-atom platinum dictates its behavior and performance in CO oxidation.
• Understanding these structure-reactivity relationships is vital for designing efficient and durable automotive catalysts.