DFT study of CO adsorption on Ag₈M and Ag₁₄M clusters (M = Au, Pd, Pt)

In this study, we use and compare the GGA (PBE), GGA+vdw (optB88) and meta-GGA (SCAN+rVV10) functionals to systematically investigate the adsorption of CO on the bimetallic Ag₈M and Ag₁₄M (M = Au, Pd, Pt) clusters. We explore how such adsorption process of CO on size-selected gas phased clusters is affected by its size and alloying as small bimetallic clusters have distinctive catalytic properties compared to its bulk counterpart. To determine the preferred adsorption site of CO, we compute adsorption energies on different adsorption sites for the bimetallic clusters and examine how it depends on the choice of functionals. We demonstrate the effect of CO adsorption on the electronic properties of these bimetallic clusters. The preferred site of CO is analyzed using Bader charge analysis to study its interaction with the bimetallic clusters and how it changes depending on the size and composition of the bimetallic clusters is also investigated. Such preliminary study is a key step in the field of catalysis and an important phase in CO oxidation reaction.