O₂ activation by AuAg clusters on a defective (100)MgO surface

Area of Science:

• Computational materials science
• Surface chemistry
• Catalysis

Background:

• Supported bimetallic clusters are vital for various catalytic applications.
• Understanding their electronic properties and interactions with supports is key to designing efficient catalysts.
• Oxygen activation by metal clusters is a fundamental step in many oxidation reactions.

Purpose of the Study:

• To investigate the electronic properties of supported dispersed bimetallic Au_nAg_m clusters (n + m = 6).
• To determine the influence of cluster size, geometry, and composition on O₂ activation.
• To elucidate the role of charge transfer from defective MgO supports in O₂ activation.

Main Methods:

• Supercell-density functional theory (DFT) calculations were employed.
• Clusters were studied in gas-phase, on pristine (100)MgO, and on defective (100)MgO F-centers.
• The Mexican enhanced genetic algorithm was used for global geometry optimization.

Main Results:

• Oxygen (O₂) activation is significantly dependent on the gold-silver (Au_nAg_m) ratio.
• Both gold and silver play distinct roles in O₂ dissociation and weakening the oxygen-cluster bond.
• Charge transfer from the MgO support enhances O₂ activation.

Conclusions:

• The Au_nAg_m ratio critically influences O₂ activation on MgO supports.
• The interplay between metals and the support facilitates O₂ dissociation, potentially enabling catalytic oxidation processes.
• These findings provide insights for designing advanced catalysts for CO and NO_x oxidation.