Reaction-driven evolutions of Pt states over Pt-CeO2 catalysts during CO oxidation

Pt-CeO2 catalysts had been comprehensively investigated on the structure-performance relationships in various applications. However, reaction-driven structural dynamics are still in heavily debate. In this study, we tried to track the evolutions of Pt states during CO oxidation. It was found that the activities are not in line with Pt loading amounts; the reactivity started to sharply decrease and the “hysteresis loop” in activity would appear when Pt loading amount is more than 0.25 %. Combining the analyses of chemisorption and spectroscopy technologies, we concluded that Pt single atoms are prone to aggregate into Pt clusters while Pt nanoparticles suffer an oxidation process and gradually form a new Pt species-PtxOy ensembles with the elevated reaction temperatures. Density functional theory calculations further revealed that the different adsorption properties of CO and O2 on Pt species with different initial sizes are the primary causes of different evolution behaviors.