<p>Understanding the solvation structures of OH<sup>−</sup> and H<sub>3</sub>O<sup>+</sup> at metal interfaces is crucial for developing efficient electrochemical devices. In this paper, we present a detailed investigation of the solvation structures of OH<sup>−</sup> and H<sub>3</sub>O<sup>+</sup> near gold electrodes under alkaline and acidic aqueous conditions, using ab initio molecular dynamics simulations at controlled surface charge density conditions. Our findings reveal that the adsorption tendencies of OH<sup>−</sup> and H<sub>3</sub>O<sup>+</sup> are strongly influenced by the oscillating net atomic charge of water normal to the electrified interface in concert with the distinct solvation patterns of these charge defects. While OH<sup>−</sup> preferentially adsorbs onto the gold surface within the first water layer, the positive net atomic charge restricts the closest approach of H<sub>3</sub>O<sup>+</sup> to beyond the first water layer. We unveil resting and active states that support charge transfer processes at the gold/water interface, which critically involve Au atoms in a unique Grotthuss-like mechanism.</p>

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Distinct solvation patterns of OH versus H3O+ charge defects at electrified gold/water interfaces govern their properties

  • Chanbum Park,
  • Soumya Ghosh,
  • Harald Forbert,
  • Dominik Marx

摘要

Understanding the solvation structures of OH and H3O+ at metal interfaces is crucial for developing efficient electrochemical devices. In this paper, we present a detailed investigation of the solvation structures of OH and H3O+ near gold electrodes under alkaline and acidic aqueous conditions, using ab initio molecular dynamics simulations at controlled surface charge density conditions. Our findings reveal that the adsorption tendencies of OH and H3O+ are strongly influenced by the oscillating net atomic charge of water normal to the electrified interface in concert with the distinct solvation patterns of these charge defects. While OH preferentially adsorbs onto the gold surface within the first water layer, the positive net atomic charge restricts the closest approach of H3O+ to beyond the first water layer. We unveil resting and active states that support charge transfer processes at the gold/water interface, which critically involve Au atoms in a unique Grotthuss-like mechanism.