Different reaction pathways of CO oxidation at the surface of trimetallic nanoclusters, Au_(5-x-y)Ag_xCu_y of varying compositions with 2 ≤ x + y ≤ 4 (x,y >0) are investigated. The starting point of all pathways is the surface reaction between adsorbed CO and O₂ via the Langmuir-Hinshelwood mechanism. The conventional reaction pathway leads to the formation of intermediate Au_(5-x-y)Ag_xCu_y.O* followed by areaction with CO to release CO₂. However, on these trimetallic clusters, the formation of the nanocluster-carbonate adduct is greatly facilitated, which is known to poison the catalytic surface because of its greater stability. Here, we propose a possible Eley-Rideal (ER) pathway leading to carbonate decomposition and catalytic surface regeneration. This ER-pathway involves interaction between nanocluster-carbonate adductand CO in the gaseous state, forming Au_(5-x-y)Ag_xCu_y.O₂COCO*, which decomposes to release CO₂. The study suggests the best trimetallic clusters for CO oxidation are the ones where both reaction sites are Agsites.

Different reaction pathways of CO oxidation at the surface of trimetallic nanoclusters, Au_(5-x-y)Ag_xCu_y, are investigated. These include the conventional LH-LH pathway and a newer alternative LH-ER pathway. The proposed LH-ER pathway involves an interaction between nanocluster-carbonate adduct and CO(g), forming Au_(5-x-y)Ag_xCu_y.O₂COCO*, which decomposes to release CO₂.