CO oxidation mechanism on CeO(2)-supported Au nanoparticles

Area of Science:

• Computational Chemistry
• Materials Science
• Surface Science
• Catalysis

Background:

• Cerium dioxide (CeO2) is a crucial support material in heterogeneous catalysis, known for its oxygen storage capacity.
• Gold nanoparticles (Au NPs) exhibit unique catalytic properties, particularly for oxidation reactions.
• Surface oxygen vacancies on CeO2 are experimentally observed and influence its reactivity.

Purpose of the Study:

• To investigate the effect of oxygen vacancies on the catalytic activity of Au NPs supported on CeO2 for CO oxidation.
• To elucidate the reaction mechanisms involved in CO oxidation on both stoichiometric and oxygen-vacancy-rich CeO2 surfaces.
• To provide insights for designing improved supported Au catalysts.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to model and analyze the catalytic processes.
• Comparison of CO oxidation pathways for a Au(13) nanoparticle on stoichiometric CeO2 (Au(13)@CeO2-STO) versus CeO2 with three oxygen vacancies (Au(13)@CeO2-3VAC).
• Analysis of three proposed CO oxidation mechanisms: coadsorbed O2, lattice oxygen, and O2 bound to a Au-Ce(3+) anchoring site.

Main Results:

• Oxygen vacancies on the CeO2 surface create a new CO oxidation pathway involving O2 bound to a Au-Ce(3+) anchoring site.
• The presence of vacancies significantly alters the reaction mechanism and enhances catalytic activity.
• DFT calculations reveal the energetic favorability of vacancy-assisted pathways.

Conclusions:

• Oxygen vacancies play a critical role in enhancing the CO oxidation catalytic activity of CeO2-supported Au NPs.
• A design strategy involves lowering the vacancy formation energy of the support and using reducible oxides to create anchoring sites for O2.
• This study offers a pathway for developing more efficient supported gold catalysts for CO oxidation.