CO oxidation catalyzed by silver nanoclusters: mechanism and effects of charge

The mechanism of the CO oxidation promoted by a neutral Ag-55 cluster was investigated extensively, using density functional theory calculations. The CO oxidation process catalyzed by anionic and cationic Ag-55 clusters was also studied, to clarify the effects of the charge state. The Eley-Rideal (ER) and Langmuir-Hinshelwood (LH) mechanisms were discussed in detail. Six reaction pathways were found for the Ag-55-mediated CO oxidation. It was found that the ER mechanism competed with the LH mechanism. The rate-limiting step of the CO oxidation was the reaction of CO with the Ag55O species. All of the anionic, neutral, and cationic Ag-55 clusters were able to promote CO oxidation at low temperatures. The present results enrich our understanding of the catalytic oxidation of CO by nano-sized Ag-based catalysts.