ct9b00717_si_001.pdf (567.95 kB)
Unified Approach to Implicit and Explicit Solvent Simulations of Electrochemical Reaction Energetics
journal contribution
posted on 2019-11-19, 20:36 authored by Joseph
A. Gauthier, Colin F. Dickens, Hendrik H. Heenen, Sudarshan Vijay, Stefan Ringe, Karen ChanOne of the major open challenges in ab initio simulations
of the electrochemical interface is the determination of electrochemical
barriers under a constant driving force. Existing methods to do so
include extrapolation techniques based on fully explicit treatments
of the electrolyte, as well as implicit solvent models which allow
for a continuous variation in electrolyte charge. Emerging hybrid
continuum models have the potential to revolutionize the field, since
they account for the electrolyte with little computational cost while
retaining some explicit electrolyte, representing a “best of
both worlds” method. In this work, we present a unified approach
to determine reaction energetics from fully explicit, implicit, and
hybrid treatments of the electrolyte based on a new multicapacitor
model of the electrochemical interface. A given electrode potential
can be achieved by a variety of interfacial structures; a crucial
insight from this work is that the effective surface
charge gives a good proxy of the local potential, the true driving
force of electrochemical processes. In contrast, we show that the
traditionally considered work function gives rise to multivalued functions
depending on the simulation cell size. Furthermore, we show that the
reaction energetics are largely insensitive to the countercharge distribution
chosen in hybrid implicit/explicit models, which means that any of
the myriad implicit electrolyte models can be equivalently applied.
This work thus paves the way for the accurate treatment of ab initio
reaction energetics of general surface electrochemical processes using
both implicit and explicit electrolytes.