In Situ Visualization and Mechanistic Understandings on Facet-Dependent Atomic Redispersion of Platinum on CeO 2 .

Redispersion is an effective method for regeneration of sintered metal-supported catalysts. However, the ambiguous mechanistic understanding hinders the delicate controlling of active metals at the atomic level. Herein, the redispersion mechanism of atomically dispersed Pt on CeO 2 is revealed and manipulated by in situ techniques combining well-designed model catalysts. Pt nanoparticles (NPs) sintered on CeO 2 nano-octahedra under reduction and oxidation conditions, while redispersed on CeO 2 nanocubes above ∼500 °C in an oxidizing atmosphere. The dynamic shrinkage and disappearance of Pt NPs on CeO 2 (100) facets was directly visualized by in situ TEM. The generated atomically dispersed Pt with the square-planar [PtO 4 ] 2+ structure on CeO 2 (100) facets was also confirmed by combining Cs-corrected STEM and spectroscopy techniques. The redispersion and atomic control were ascribed to the high mobility of PtO 2 at high temperatures and its strong binding with square-planar O 4 sites over CeO 2 (100). These understandings are important for the regulation of atomically dispersed platinum catalysts.