(Invited) First-Principles Simulations of Electrochemical Reactions and Properties at Water|Pt Interfaces
Authors: Ikeshoji Tamio 
Published: February 2020

A first step for understanding the electrochemical reactions from fundamental point of view is ab-initio calculations to find the reaction path and the energy profile along the reaction cooprdinate. More reliable and more realistic way including solvent, temperature, electrolyte, electrode interface, etc., is to use first-principles molecular dynamics. A pioneer work in this direction is that by Ishiwaka and co-workers [1]. They used a cluster Pt with water molecules. They followed the first step of the hydrogen evolution, i.e. H adsorption on Pt. They controlled the electrode potential by changing the number of electrons in the system.
We used the slab model under the periodic boundary conditions [2]. Electrode potential was controlled by using the effective screening medium (ESM) [3] separated from the water layer on Pt with a vacuum layer. Hydrogen adsorption from H3O+was observed with a charge transfer between Pt layer and the hydronium ion.
Water structure on Pt is important properties to understand fuel cell reactions and H2/O2 evolution from water by electrochemical reactions [6-11]. H-down adsorption structure of water molecules with well-developed hydrogen network with H3O+ was observed on Pt(111) surface. O-H stretching vibrations of H2O on Pt was in a function of the electrode potential.
Specific adsorption on Pt electrode is also an important factor in the electrochemical reaction on it. SO4
2– and HSO4
–adsorptions were observed on the potential controlled Pt [12,13]. Vibration properties of adsorbed (bi)sulfate on the Pt(111) surface were obtained by FPMD with the cluster and slab models.
Our work shown here has been performed with collaboration among M. Otani (AIST), I. Hamada (NIMS), O. Sugino (Univ. Tokyo), Y. Morikawa (Osaka Univ.), Y. Okamoto (NEC), and Y. Qian (FC-Cubic).
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