Water Structure and Mechanisms of Proton Discharge on Platinum Electrodes: Empirical Valence Bond Molecular Dynamics Trajectory Studies

3 years ago

Water Structure and Mechanisms of Proton Discharge on Platinum Electrodes: Empirical Valence Bond Molecular Dynamics Trajectory Studies

Eckhard Spohr, Johannes Wiebe

Abstract

We present a comparative analysis of molecular dynamics trajectory studies of the influence of surface charge, ion strength, and ion adsorption on the interfacial water structure and the possible pathways of proton transport and discharge on negatively charged platinum(111) electrodes. The model used is a reactive force field based on a nine-state empirical valence bond model. It incorporates both proton transfer between water molecules and simultaneous electron and proton transfer to the metal (discharge). The interfacial water polarization is the result of the competition between the electrical field influence of the smooth surface charge and the point-like local charges of adsorbed positive or negative ions, which leads to variations of the prevalent proton discharge pathways depending on system composition.

Graphical Abstract

In trajectory calculations of proton adsorption and discharge from aqueous solutions onto charged platinum electrodes, the presence of electrolytes in the adsorbate layer influences proton discharge mechanisms via changes in water orientation and via exclusion of discharge sites through repulsive cation-proton interactions.

Publisher URL: https://link.springer.com/article/10.1007/s12678-017-0398-2

DOI: 10.1007/s12678-017-0398-2