Stable Pd-Doped Ceria Structures for CH₄ Activation and CO Oxidation.

Area of Science:

• Materials Science
• Surface Chemistry
• Catalysis

Background:

• Palladium-doped ceria (Pd-CeO2) is known for CO oxidation catalysis.
• Existing surface models fail to explain CO adsorption on Pd-CeO2.
• The precise atomic configuration of dopants significantly impacts surface properties.

Purpose of the Study:

• To investigate a novel surface structure of palladium-doped ceria (Pd-CeO2(111)).
• To understand the adsorption and reaction mechanisms of CO and methane on this new surface.
• To explore the potential of this structure for single-atom catalysis.

Main Methods:

• Computational modeling and surface structure analysis.
• Density Functional Theory (DFT) calculations.
• Analysis of reaction pathways and energy barriers for CO oxidation and C-H bond cleavage.

Main Results:

• A new square planar configuration for Pd atoms on CeO2(111) was identified, differing from previous octahedral models.
• Oxygen removal from the doped structure is energetically favorable, creating defects.
• The defective Pd-CeO2 surface exhibits activity for CO oxidation and methane C-H bond activation.
• Moderate CO adsorption energy and dynamic Pd behavior contribute to an efficient CO oxidation cycle.

Conclusions:

• The square planar Pd configuration on CeO2 offers a more open coordination environment.
• These thermally stable structures, also observed for Ni and Pt, are promising for single-atom catalyst development.
• The findings provide a new structural basis for understanding and designing ceria-based catalysts.