CO Oxidation Mechanisms on CoO-Pt Thin Films

Area of Science:

• Surface science
• Heterogeneous catalysis
• Materials science

Background:

• Understanding CO oxidation on metal-oxide interfaces is crucial for catalysis.
• Cobalt oxides (CoO) on platinum (Pt) are model systems for studying reducible oxide interactions.
• The role of oxygen vacancies in CO oxidation on CoO films requires detailed investigation.

Purpose of the Study:

• To investigate the CO oxidation reaction on submonolayer and multilayer CoO films on Pt(111).
• To elucidate the influence of oxygen vacancies in CoO films on CO oxidation activity.
• To understand CO adsorption and carbonate formation pathways on CoO surfaces.

Main Methods:

• Operando ambient pressure X-ray photoelectron spectroscopy (AP-XPS).
• High-pressure scanning tunneling microscopy (HP-STM).
• Density functional theory (DFT) calculations.

Main Results:

• Partially oxidized CoO films with oxygen vacancies exhibit significantly enhanced CO oxidation to CO2 at room temperature.
• CoO films lacking oxygen vacancies show minimal CO2 formation and adsorb CO as stable carbonates.
• Carbonate formation preferentially occurs at the edges of submonolayer CoO islands, deactivating these sites.

Conclusions:

• Oxygen vacancies in CoO films are key to promoting CO oxidation.
• The presence or absence of vacancies dictates the reaction pathway (CO2 formation vs. carbonate adsorption).
• Understanding vacancy-driven mechanisms and edge effects is vital for designing efficient catalysts.