Carbon Monoxide Oxidation on Ceria-Supported Nanoclusters

Area of Science:

• Surface Science
• Catalysis
• Computational Chemistry

Background:

• Cerium oxide (CeO2) is a crucial support material in heterogeneous catalysis due to its oxygen storage capacity.
• Platinum (Pt) and Palladium (Pd) nanoclusters are widely used as active catalytic components.
• Understanding the CO oxidation mechanism on metal/CeO2 interfaces is vital for designing efficient catalysts.

Purpose of the Study:

• To investigate and compare the minimum energy pathways for CO oxidation on Pt/CeO2 and Pd/CeO2 nanoclusters.
• To elucidate the role of the cerium oxide support and metal cluster in the oxidation process.
• To correlate theoretical findings with experimental observations of catalytic activity.

Main Methods:

• Periodic density functional theory (DFT) calculations were employed to determine reaction pathways and energy barriers.
• Analysis of the interaction between CO, oxygen species, and the metal-ceria interface.
• Experimental validation using temperature-programmed reduction (TPR) to assess catalytic performance.

Main Results:

• On Pt/CeO2, CO oxidation primarily utilizes lattice oxygen from the CeO2 support at the interface, resulting in a low energy barrier.
• On Pd/CeO2, CO oxidation predominantly involves oxygen species adsorbed on the Pd nanocluster.
• Experimental TPR data showed a lower CO oxidation temperature for Pd/CeO2 compared to Pt/CeO2.

Conclusions:

• The mechanism of CO oxidation differs significantly between Pt/CeO2 and Pd/CeO2 nanoclusters.
• Pd/CeO2 demonstrates higher catalytic efficiency for CO oxidation due to a lower energy barrier associated with its surface oxygen species.
• DFT calculations provide valuable insights into the structure-activity relationships for supported metal catalysts.