Spectroscopic investigation of the structural transformation of Ru in the Ru/CeO₂ catalyst

The catalytic performance of supported catalysts is greatly determined by the electronic and geometric structures of the active metal in the catalysts. A comprehensive recognition of the dynamic transformation of the active metal can contribute to a deep understanding of the active sites and the rational design of advanced catalysts. In this study, the status of Ru in the Ru/CeO2 catalyst was intensively investigated in oxidative (O-2), inert (N-2, Ar), and reductive (H-2, CO) atmospheres by an in situ spectroscopic technique. It was found that Ru single atoms and nanoclusters could undergo reversible transformations under oxidative and reductive atmospheric conditions. Even after treatment under an inert atmosphere, obvious structural changes of the Ru species were observed, indicating the structure sensitivity of Ru supported on CeO2 to environmental changes. Besides, the differences in reaction activity for CO oxidation of the Ru/CeO2 catalysts after different pretreatments clearly illustrated that the dynamic transformations of Ru greatly influence the catalytic performances. This study presents a typical case for understanding the reversible transformation behavior of Ru species and emphasizes the significant impact of the active metal status on the catalytic activity.