An alternative decomposition reaction pathway for CO oxidation at Au5-x-yAgxCuy (2 ≤ x + y ≤ 4) nanoclusters

Abstract

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 a reaction 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 adduct and 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 Ag-sites.

Graphical abstract

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.