Adaptive Dynamic Evolution of Substitutional Pt Single Atoms in CeO2 for CO Oxidation

Platinum-substitutional ceria solid solutions (PtxCe1–xO2) have attracted considerable attention owing to their high stability and activity for low-temperature CO oxidation. However, their catalytic behavior and reactant-induced structural evolution under reaction conditions remain under debate. Here, we investigate the CO-induced structural evolution of substitutional Pt single-atom sites in CeO2(111) and their dynamically catalytic activity for low-temperature CO oxidation by means of density functional theory (DFT) calculations. Our results show that the commonly proposed octahedrally coordinated Pt species are unstable in a CO atmosphere since CO adsorbed on Pt readily reacts with lattice oxygen with a low energy barrier. The resulting CO2 formation induces a dynamic evolution of the Pt coordination environment, driving the transformation from octahedral coordination to a more energetically stable square-planar configuration. In addition, oxygen vacancies (VO) and CO adsorption synergistically promote the displacement of substitutional Pt atoms, leading to the formation of distorted Pt–CO complexes adjacent to vacancy sites that serve as the active centers for CO oxidation. Ab initio molecular dynamics (AIMD) and deep-potential molecular dynamics (DPMD) simulations further verify that the octahedral-to-square-planar dynamic evolution occurs spontaneously, while similar coordination evolution on the various ceria facets indicates that this behavior is not limited to CeO2(111) but is a general feature of Pt1-substituted CeO2. Further experimental characterization results corroborate the calculated coordination evolution of Pt sites and support the proposed dynamic structural transformation. These findings provide atomistic insights into the reaction-induced structural evolution of Pt species in CeO2 and clarify the origin of the catalytic activity of Pt-substituted ceria for low-temperature CO oxidation.