Redox functionality mediated by adsorbed oxygen on a Pd oxide film over a Pd(100) thin structure: a first-principles...

Area of Science:

• Surface Science
• Computational Chemistry
• Catalysis

Background:

• Palladium oxide (PdO) films on Pd(100) surfaces are crucial in catalytic processes.
• Understanding oxygen adsorption and mobility on these surfaces is key to optimizing reactions.

Purpose of the Study:

• To determine stable oxygen sites on PdO films over Pd(100) surfaces.
• To investigate the energetics and dynamics of oxygen adsorption and surface reactions.
• To assess the potential of these systems for catalytic applications.

Main Methods:

• First-principles electronic structure calculations using the generalized gradient approximation.
• Nudged elastic band method to evaluate energy barriers for oxygen atom motion.

Main Results:

• Identified stable oxygen adsorption sites: bridging two twofold-coordinated Pd atoms or bridging a twofold- and a fourfold-coordinated Pd atom.
• CO oxidation and N(2)O reduction mediated by the PdO film are exothermic.
• A low energy barrier (~0.45 eV) for oxygen atom translation indicates high surface oxygen mobility at elevated temperatures.

Conclusions:

• The PdO film over Pd(100) supports dynamic surface oxygen, enabling continuous redox reactions.
• The local structure of the PdO film, featuring twofold-coordinated Pd atoms, is similar to that in Pd catalysts for Suzuki-Miyaura cross-coupling.
• These findings suggest potential for oxygen-adsorbed PdO films in catalyzing reactions involving NOx and CO under specific conditions.