Probing Adsorption Interactions In Metal-Organic Frameworks Using X-ray Spectroscopy and Density Functional Theory

ORAL

Abstract

Metal-organic frameworks (MOFs) are currently among the most promising materials for gas separation applications such as carbon capture. We explore the local electronic signatures of molecular adsorption at coordinatively unsaturated binding sites in the metal-organic framework Mg-MOF-74 using X-ray spectroscopy and first principles calculations. \textit{In situ} measurements at the Mg $K$-edge reveal distinct pre-edge absorption features associated with the unique, open coordination of the Mg sites. These spectral features are suppressed upon adsorption of CO$_{2}$ and $N,N'$-dimethylformamide. Density functional theory shows that these spectral changes arise from modifications of local symmetry around the Mg sites upon gas uptake and are strongly dependent on the metal-adsorbate binding strength. Similar sensitivity to local symmetry is expected for any open metal site, making X-ray spectroscopy an ideal tool for examining adsorption in such MOFs.

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Authors

  • Walter Drisdell

    Lawrence Berkeley National Laboratory

  • Roberta Poloni

    SIMAP, laboratoire de Recherche sur les Mat\'eriaux, Grenoble

  • Thomas McDonald

    University of California, Berkeley

  • Jeffrey Long

    University of California, Berkeley

  • Berend Smit

    Dept. of Chemical and Biomolecular Engineering, University of California, Berkeley; Materials Sciences Division, LBNL, University of California, Berkeley

  • Jeffery B. Neaton

    Department of Physics, UC-Berkeley; Molecular Foundry, LBNL, Molecular Foundry, LBNL, Department of Physics, UC Berkeley, Molecular Foundry, LBNL and Dept. Physics, UC Berkeley, Molecular Foundry, Lawrence Berkeley National Laboratory and Department of Physics, University of California, Berkeley, UC Berkeley, Dept of Physics; Materials Science Division, LBNL, Molecular Foundry, Lawrence Berkeley National Laboratory; Department of Physics, UC-Berkeley, The Molecular Foundry, LBNL; Dept. of Physics, University of California, Berkeley, Lawrence Berkeley National Laboratory, UC Berkeley Department of Physics, Lawrence Berkeley Natl Lab and Department of Physics, UC-Berkeley, Physics Department, UC Berkeley; Molecular Foundry, Lawrence Berkeley National Lab

  • David Prendergast

    Lawrence Berkeley National Laboratory, The Molecular Foundry, Lawrence Berkeley National Laboratory, Lawrence Berkeley National Lab

  • Jeffrey Kortright

    Lawrence Berkeley National Laboratory