From Single Atoms to Clusters: Unraveling the Structural Evolution of Pt/CeO₂ for Enhanced CO Oxidation

The structural evolution of catalysts and the identification of active sites are critical yet challenging aspects of heterogeneous reactions. In this work, we investigate the structural evolution of Pt/CeO₂ catalysts during CO oxidation by using theoretical calculations, focusing on the influence of initial catalyst states on the resulting active sites and reactivity. Our findings reveal that under the reaction conditions, single Pt atoms gradually aggregate into Pt clusters. When single Pt atoms are substituted for surface Ce atoms (Pt_in), the resulting small clusters (Pt) are exclusively formed based on Pt_in. However, when both Pt_in and surface-adsorbed Pt atoms (Pt_ad) coexist, additional small surface-adsorbed clusters (Pt) are generated. An increase in the Pt_ad/Pt_in ratio leads to a higher proportion of clusters at the active sites, which correlates with enhanced CO oxidation activity as the number of clusters increases. This study underscores the importance of understanding catalyst evolution and active site dynamics under the reaction conditions, providing theoretical insights for the rational design of more efficient catalysts.