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Abstract Encapsulation of metal nanoparticles within oxide materials has been shown as an effective strategy to improve activity, selectivity, and stability in several catalytic applications. Several approaches have been proposed to encapsulate nanoparticles, such as forming core‐shell structures, growing ordered structures (zeolites or metal‐organic frameworks) on nanoparticles, or directly depositing support materials on nanoparticles. Here, a general nanocasting method is demonstrated that can produce diverse encapsulated metal@oxide structures with different compositions (Pt, Pd, Rh) and multiple types of oxides (Al2O3, Al2O3‐CeO2, ZrO2, ZnZrOx, In2O3, Mn2O3, TiO2) while controlling the size and dispersion of nanoparticles and the porous structure of the oxide. Metal@polymer structures are first prepared, and then the oxide precursor is infiltrated into such structures and the resulting material is calcined to form the metal@oxide structures. Most Pt@oxides catalysts show similar catalytic activity, demonstrating the availability of surface Pt sites in the encapsulated structures. However, the Pt@Mn2O3sample showed much higher CO oxidation activity, while also being stable under aging conditions. This work demonstrated a robust nanocasting method to synthesize metal@oxide structures, which can be utilized in catalysis to finely tune metal‐oxide interfaces.
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Monolayer Support Control and Precise Colloidal Nanocrystals Demonstrate Metal–Support Interactions in Heterogeneous Catalysts
Abstract Electronic and geometric interactions between active and support phases are critical in determining the activity of heterogeneous catalysts, but metal–support interactions are challenging to study. Here, it is demonstrated how the combination of the monolayer‐controlled formation using atomic layer deposition (ALD) and colloidal nanocrystal synthesis methods leads to catalysts with sub‐nanometer precision of active and support phases, thus allowing for the study of the metal–support interactions in detail. The use of this approach in developing a fundamental understanding of support effects in Pd‐catalyzed methane combustion is demonstrated. Uniform Pd nanocrystals are deposited onto Al2O3/SiO2spherical supports prepared with control over morphology and Al2O3layer thicknesses ranging from sub‐monolayer to a ≈4 nm thick uniform coating. Dramatic changes in catalytic activity depending on the coverage and structure of Al2O3situated at the Pd/Al2O3interface are observed, with even a single monolayer of alumina contributing an order of magnitude increase in reaction rate. By building the Pd/Al2O3interface up layer‐by‐layer and using uniform Pd nanocrystals, this work demonstrates the importance of controlled and tunable materials in determining metal–support interactions and catalyst activity.
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- Award ID(s):
- 1753585
- PAR ID:
- 10445856
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 33
- Issue:
- 44
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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