Stripping away ion hydration shells in electrical double-layer formation: Water networks matter.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34782461.
- Also identified by DOI 10.1073/pnas.2108568118 and PMC identifier 8617503.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
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<sup>+</sup> is attracted toward the electrode at the smallest applied negative potentials, stripping of the Cl<sup>-</sup> 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.