Electron Affinity of Liquid Water

ORAL

Abstract

Understanding redox reactions in aqueous environments requires a precise knowledge of the ionization potential and electron affinity of liquid water. The former has been measured, but the latter remains unknown. We predict the electron affinity (EA) of liquid water and of its surface from first principles, coupling path-integral molecular dynamics with ab initio potentials and many-body perturbation theory calculations. Our results for the surface agree with recent pump-probe spectroscopy measurements, while those for the bulk differ from several estimates adopted in the literature. We revisit these estimates and present an updated energy diagram for an electron in water. We show that the ionization potential of the bulk and surface are almost identical; instead their EAs differ substantially, with the conduction band edge of the surface much deeper in energy than that of the bulk. We also discuss the significant impact of nuclear quantum effects on the fundamental gap and band edges of the liquid.

A. P. Gaiduk, T. A. Pham, M. Govoni, F. Paesani, and G. Galli, Nat. Commun. (submitted)

*NSERC Postdoctoral Fellowship; MICCoM center, U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division (5J-30161-0010A)

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Presenters

  • Alex Gaiduk

    • Institute for Molecular Engineering, University of Chicago

Authors

  • Alex Gaiduk

    • Institute for Molecular Engineering, University of Chicago

  • Tuan Anh Pham

    • Lawrence Livermore Natl Lab
    • Lawrence Livermore National Laboratory

  • Marco Govoni

    • Materials Science Division, Argonne National Laboratory
    • Institute for Molecular Engineering and Materials Science Division, Argonne National Lab
    • Argonne National Laboratory; University of Chicago
    • Insitute for Molecular Engineering and Materials Science Division, Argonne National Lab
    • Materials Science Division , Argonne National Laboratory
    • Argonne National Laboratory
    • Institute for Molecular Engineering, University of Chicago

  • Francesco Paesani

    • Department of Chemistry and Biochemistry, University of California, San Diego

  • Giulia Galli

    • Institute for Molecular Engineering, University of Chicago
    • Univ of Chicago
    • University of Chicago
    • Institute for Molecular Engineering, University of Chicago; Argonne National Laboratory
    • Institute for Molecular Engineering, University of Chicago, Chicago, IL, United States and Materials Science Division, Argonne National Laboratory
    • University of Chicago; Argonne National Laboratory
    • Institute for Molecular Engineering, Univ of Chicago