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Quantitative Z-Contrast Imaging of Supported Metal Complexes and Clusters—A Gateway to Understanding Catalysis on the Atomic Scale

Authors

  • Dr. Nigel D. Browning,

    Corresponding author
    1. Department of Chemical Engineering and Material Science, University of California, Davis, One Shields Avenue, Davis, CA 95618 (USA)
    2. Department of Molecular and Cellular Biology, University of California, Davis, One Shields Avenue, Davis, CA 95618 (USA)
    3. Current address: Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99352 (USA)
    • Department of Chemical Engineering and Material Science, University of California, Davis, One Shields Avenue, Davis, CA 95618 (USA)
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  • Dr. Ceren Aydin,

    1. Department of Chemical Engineering and Material Science, University of California, Davis, One Shields Avenue, Davis, CA 95618 (USA)
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  • Dr. Jing Lu,

    1. Department of Chemical Engineering and Material Science, University of California, Davis, One Shields Avenue, Davis, CA 95618 (USA)
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  • Dr. Apoorva Kulkarni,

    1. Department of Chemical Engineering and Material Science, University of California, Davis, One Shields Avenue, Davis, CA 95618 (USA)
    2. Current address: Analytical Science, Core R&D, Dow Chemical Company, Midland, MI 48667 (USA)
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  • Dr. Norihiko L. Okamoto,

    1. Department of Chemical Engineering and Material Science, University of California, Davis, One Shields Avenue, Davis, CA 95618 (USA)
    2. Current address: Department of Materials Science and Engineering, Kyoto University, Kyoto 6068501 (Japan)
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  • Prof. Volkan Ortalan,

    1. Department of Chemical Engineering and Material Science, University of California, Davis, One Shields Avenue, Davis, CA 95618 (USA)
    2. Current address: School of Materials Engineering, Purdue University, 701 West Stadium Avenue, West Lafayette, IN 47907 (USA)
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  • Dr. Bryan W. Reed,

    1. Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550 (USA)
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  • Dr. Alper Uzun,

    1. Department of Chemical Engineering and Material Science, University of California, Davis, One Shields Avenue, Davis, CA 95618 (USA)
    2. Current address: Department of Chemical and Biological Engineering, Koc University, Rumelifeneri Yolu 34450 Sariyer, Istanbul (Turkey)
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  • Prof. Bruce C. Gates

    1. Department of Chemical Engineering and Material Science, University of California, Davis, One Shields Avenue, Davis, CA 95618 (USA)
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Abstract

Z-contrast imaging in an aberration-corrected scanning transmission electron microscope can be used to observe and quantify the sizes, shapes, and compositions of the metal frames in supported mono-, bi-, and multimetallic metal clusters and can even detect the metal atoms in single-metal-atom complexes, as well as providing direct structural information characterizing the metal–support interface. Herein, we assess the major experimental challenges associated with obtaining atomic resolution Z-contrast images of the materials that are highly beam-sensitive, that is, the clusters readily migrate and sinter on support surfaces, and the support itself can drastically change in structure if the experiment is not properly controlled. Calibrated and quantified Z-contrast images are used in conjunction with ex situ analytical measurements and larger-scale characterization methods such as extended X-ray absorption fine structure spectroscopy to generate an atomic-scale understanding of supported catalysts and their function. Examples of the application of these methods include the characterization of a wide range of sizes and compositions of supported clusters, primarily those incorporating Ir, Os, and Au, on highly crystalline supports (zeolites and MgO).

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