Molecular and dissociative O₂ adsorption on the Cu₂O(111) surface

Area of Science:

• Surface Science
• Materials Chemistry
• Computational Chemistry

Background:

• Understanding oxygen adsorption on metal oxides is crucial for catalysis and materials science.
• Cuprous oxide (Cu2O) is a key material with applications in various fields.
• The Cu2O(111) surface presents a unique platform for studying surface reactions.

Purpose of the Study:

• To investigate the adsorption behavior of molecular oxygen (O2) on the Cu2O(111) surface.
• To determine the preferred adsorption states (molecular vs. dissociative) at varying O2 coverages.
• To explore the surface reconstruction and potential film formation under O2 exposure.

Main Methods:

• Spin-polarized density functional theory (DFT+U) calculations were employed.
• Atomic thermodynamics and phase diagrams were utilized for analysis.
• A Boltzmann model was used to analyze the probability distribution of adsorbed states.

Main Results:

• Dissociative O2 adsorption is favored on the reconstructed Cu2O(111) surface at low coverages (1/4 to 1 monolayer).
• At higher coverages (5/4 to 7/4 monolayers), fully dissociative and mixed molecular/dissociative adsorption are thermodynamically preferred.
• Spontaneous formation of a CuO film was observed at 1 monolayer coverage, consistent with experimental findings.
• Increased surface reconstruction and relaxation were noted at higher O2 coverages.

Conclusions:

• The adsorption mechanism of O2 on Cu2O(111) is coverage-dependent, transitioning from dissociative to mixed/fully dissociative states.
• Surface reconstruction plays a critical role in O2 adsorption and can lead to the formation of new surface phases like CuO.
• The findings provide insights into the surface chemistry of Cu2O and its interactions with oxygen.