CO oxidation catalyzed by neutral and anionic Cu20 clusters: relationship between charge and activity

Area of Science:

• Computational chemistry
• Surface science
• Catalysis

Background:

• Copper clusters are extensively studied for catalytic applications.
• Understanding CO oxidation mechanisms on metal clusters is crucial for developing efficient catalysts.

Purpose of the Study:

• To investigate the reaction mechanisms of CO and O2 on neutral and anionic Cu20 clusters.
• To compare the catalytic activity of neutral and anionic Cu20 clusters for CO oxidation.
• To explore the potential of copper clusters in CO2 chemistry.

Main Methods:

• Spin-polarized density functional theory (DFT) calculations were employed.
• Adsorption energies, reaction pathways, and reaction barriers were systematically calculated.
• Three CO oxidation mechanisms were explored: atomic oxygen, Langmuir-Hinshelwood (LH), and Eley-Rideal (ER).

Main Results:

• Anionic Cu20(-) exhibits stronger adsorption of CO and O2 compared to neutral Cu20.
• CO oxidation is more efficient on both clusters when O2 is pre-adsorbed dissociatively.
• The Eley-Rideal mechanism shows a lower reaction barrier than the Langmuir-Hinshelwood mechanism on neutral Cu20.
• CO oxidation proceeds more readily on Cu20(-) (0.1-0.3 eV barriers) than on Cu20 (0.3-0.5 eV barriers).
• Cu20(-) demonstrates enhanced binding for CO2 and facilitates the reverse reaction (CO2 to CO + O).

Conclusions:

• Anionic Cu20(-) clusters are more effective catalysts for CO oxidation than neutral Cu20 clusters.
• The enhanced catalytic activity of Cu20(-) is attributed to its electronic structure and stronger adsorption properties.
• Copper clusters, particularly anionic ones, show potential as catalysts for CO2 conversion chemistry.