Publications

Stripping away ion hydration shells in electrical double-layer formation: Water networks matter

Alfarano, S.R. and Pezzotti, S. and Stein, C.J. and Lin, Z. and Sebastiani, F. and Funke, S. and Hoberg, C. and Kolling, I. and Ma, C.Y. and Mauelshagen, K. and Ockelmann, T. and Schwaab, G. and Fu, L. and Brubach, J.-B. and Roy, P. and Head-Gordon, M. and Tschulik, K. and Gaigeot, M.-P. and Havenith, M.

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume: 118 Pages:
DOI: 10.1073/pnas.2108568118
Published: 2021

Abstract
The double layer at the solid/electrolyte interface is a key concept in electrochemistry. Here, we present an experimental study combined with simulations, which provides a molecular picture of the double-layer formation under applied voltage. By THz spectroscopy we are able to follow the stripping away of the cation/anion hydration shells for an NaCl electrolyte at the Au surface when decreasing/increasing the bias potential. While Na+ is attracted toward the electrode at the smallest applied negative potentials, stripping of the Cl2 hydration shell is observed only at higher potential values. These phenomena are directly measured by THz spectroscopy with ultrabright synchrotron light as a source and rationalized by accompanying molecular dynamics simulations and electronic-structure calculations. © 2021 National Academy of Sciences. All rights reserved.

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