posted on 2023-12-15, 19:33authored byLei Zhang, Yiming Niu, Yinghui Pu, Yongzhao Wang, Shaoming Dong, Yuefeng Liu, Bingsen Zhang, Zhong-Wen Liu
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 CeO2 is revealed and manipulated by in situ techniques
combining well-designed model catalysts. Pt nanoparticles (NPs) sintered
on CeO2 nano-octahedra under reduction and oxidation conditions,
while redispersed on CeO2 nanocubes above ∼500 °C
in an oxidizing atmosphere. The dynamic shrinkage and disappearance
of Pt NPs on CeO2 (100) facets was directly visualized
by in situ TEM. The generated atomically dispersed
Pt with the square-planar [PtO4]2+ structure
on CeO2 (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 PtO2 at high temperatures
and its strong binding with square-planar O4 sites over
CeO2 (100). These understandings are important for the
regulation of atomically dispersed platinum catalysts.