Structure sensitivity of CO oxidation on Co3O4: a DFT study

Area of Science:

• Surface Science
• Catalysis
• Computational Chemistry

Background:

• Carbon monoxide (CO) oxidation is crucial for environmental remediation and industrial processes.
• Cobalt oxide (Co(3)O(4)) is a promising catalyst for CO oxidation.
• Understanding the reaction mechanism on different Co(3)O(4) surfaces is essential for catalyst design.

Purpose of the Study:

• To investigate the CO oxidation reaction mechanism on Co(3)O(4) (110) and (111) surfaces.
• To clarify the role of surface structure and cobalt oxidation states in CO oxidation.
• To determine the rate-determining steps and activation energies for CO oxidation.

Main Methods:

• Spin-polarized density functional theory (DFT) calculations.
• Generalized Gradient Approximation + Hubbard (GGA+U) framework.
• Analysis of adsorption energies and reaction pathways.

Main Results:

• The U value significantly impacts calculated adsorption energies.
• CO oxidation proceeds via the Mars-van Krevelen mechanism involving lattice oxygen on both (110)-B and (111)-B surfaces.
• Pre-adsorbed O(2) enhances CO oxidation on (110)-A/(111)-A surfaces.
• CO oxidation is structure-sensitive, with the (110) surface being more reactive than the (111) surface.
• Both lattice oxygen (O(2f)) and Co(3+) ions are identified as active sites controlling catalytic activity.

Conclusions:

• The reaction mechanism and active sites for CO oxidation on Co(3)O(4) surfaces are elucidated.
• Catalytic activity is influenced by surface facets and the oxidation state of cobalt ions.
• DFT calculations provide valuable insights into heterogeneous catalysis.