(695c) Multi-Scale Modeling of Electrocatalytic Processes within the Electrochemical Double Layer

Electrocatalysis is a promising technology due to its conversion of electrical to chemical energy at ambient reaction conditions while controlling the selectivity and kinetics using an applied voltage. Despite its promising potential, the rational design of electrocatalysts is difficult due to the complex interplay of the electrode-electrolyte interface with the catalyst, impacting the kinetics of electrochemical reactions. Theoretical modeling of these systems is not trivial due to the large length and time scales of electrocatalytic systems, which is computationally daunting for “exact” computational models to capture the complexity of solvation and electrification. While more approximate approaches are more computationally tractable, they lack predictability and ability discern results between unphysical model parameters, questioning these predictions.

We introduce a computational efficient compartmentalized approach that can be used to model electrochemical activation barriers, reaction energetics, and equilibrium adsorption potentials within the EDL while discerning the choices utilized in our model. Our model utilizes the advantages of density functional theory (DFT) and force-field molecular dynamics (FF-MD) methods to incorporate electrification and solvation within the EDL. DFT calculations are utilized to represent the local electronic structure of the adsorbate on the electrocatalysts with the inclusion of explicit H₂O to represent micro solvation. We incorporate electrode double-layer theory described by a Helmholtz model to incorporate electrification within the EDL with the advantage of selecting two discernable model parameters, dielectric constant and width of the EDL. We lastly incorporate a FF-MD model of the electrode-electrolyte that can model the extended dynamic solvation effects and electrification outside of the DFT length scale while rationally informing the parameters of our EDL model. Our model predicts that larger dipole moment changes along the reaction path indicate larger magnitude of EDL effects on activation barriers and equilibrium adsorption potentials, predicting that these systems are more sensitive to the model parameters used.