Support‐Mediated Reversible Redox Dynamics of Pt and Au on CeO 2 at Room Temperature

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Abstract
Noble metals such as platinum and gold are widely regarded as resistant to oxidation under ambient conditions. We show that interfacing these metals with a reducible oxide alters their redox behavior through dynamic metal–support interactions. Using in situ environmental transmission electron microscopy, we visualize reversible room‐temperature redox cycling of Pt and Au nanoparticles on CeO 2 under alternating O 2 and vacuum. Oxygen vacancies in the partially reduced support dissociate O 2 into reactive atomic oxygen, which spills over to oxidize the supported metal, driving complete conversion of Pt to crystalline Pt 3 O 4 , and the formation of ordered oxide species on Au. For Pt/CeO 2 , redox cycling also induces a reversible wetting–dewetting restructuring in which oxidation promotes dewetting into three‐dimensional oxide islands, whereas reduction drives wetting of metallic Pt into atomically thin rafts, progressively increasing metal dispersion. In contrast, Au/CeO 2 exhibits self‐limiting surface oxidation, highlighting the role of metal identity in governing restructuring pathways. Density functional theory modeling shows that this process is sustained by a Cabrera–Mott‐type field‐assisted oxidation mechanism enabled by the CeO 2 support. These results establish reducible oxides as active redox partners rather than passive supports, providing a mechanistic framework for designing low‐temperature oxidation catalysts through support‐driven dynamic chemistry.
Funding Information
  • Division of Materials Sciences and Engineering (DE‐SC0001135)
  • Brookhaven National Laboratory

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