Thermally Triggered Redox Flexibility of Pt/CeO₂ Cluster Catalyst Against In-Situ Atomic Redispersion

For supported catalysts, the redispersion of aggregated metal sites into single atoms is dictated by the reactant-induced metal-support interaction, which may also deteriorate the intrinsic activity. Here we discovered the spontaneous redispersion of CeO₂-supported Pt clusters into Pt single atoms during catalytic CO oxidation, driven by Pt-CeO₂ interaction with surface hydroxyls as the key stabilizer. This structural evolution was accompanied by deactivation, leading to inferior catalytic activity. After achieving the clear distinction of PtO_x clusters and Pt single atoms, we propose a thermal aging strategy to preserve the Pt clusters against redispersion. The high-temperature calcination at 800 °C significantly removed the surface hydroxyls of Pt/CeO₂, thereby eliminating the anchoring sites for Pt redispersion and consequently preserving the Pt clusters. Moreover, the Ce³⁺/Ce⁴⁺ redox cycles were triggered, enabling the interfacial Ce³⁺ sites to fulfill O₂ activation. Together with the enhanced CO adsorption on Pt clusters over single atoms, this redox flexibility in valence change delivered superior activity for CO oxidation.