Understanding oxygen transfer on ceria with Pt single atoms for surface reaction

Area of Science:

• Catalysis
• Materials Science
• Surface Chemistry

Background:

• Reducible metal oxides, like ceria (CeO2), are crucial for surface reactions due to their oxygen activation and transfer capabilities.
• Ceria's Ce3+/Ce4+ redox property follows the Mars van Krevelen mechanism, essential for catalytic processes.
• Isolated ceria domains on alumina prevent inter-domain oxygen transfer, allowing for focused study.

Purpose of the Study:

• To investigate the influence of ceria domain size on oxygen transfer mechanisms (O2 activation and lattice oxygen transfer) in Pt/CeO2-Al2O3 catalysts.
• To elucidate the distinct roles of small and large ceria domains in catalytic reactions under varying oxygen conditions.
• To correlate experimental findings with molecular dynamics simulations for a comprehensive understanding.

Main Methods:

• Preparation of Pt/CeO2-Al2O3 catalysts with controlled ceria domain sizes (3.7, 5.6, 7.3 nm).
• Characterization of catalysts focusing on O2 activation and lattice oxygen transfer.
• CO oxidation experiments under varying O2 concentrations.
• Large-scale molecular dynamics simulations using neural network potentials.

Main Results:

• O2 activation is most efficient in small ceria domains (3.7 nm).
• Larger ceria domains (7.3 nm) show reduced O2 activation but enhanced lattice oxygen transfer.
• CO oxidation activity shows an inverse trend depending on O2 availability, linked to ceria domain size.
• Simulations confirm the size-dependent oxygen transfer behavior.

Conclusions:

• Ceria domain size critically dictates the dominant oxygen transfer pathway (activation vs. lattice transfer).
• Optimizing ceria domain size is key for designing efficient catalysts for reactions like methane oxidation.
• This study provides a fundamental platform for understanding and engineering metal oxide catalysts.