Electric double layers form at electrode-electrolyte interfaces and often play defining roles in governing electrochemical reaction rates and selectivity. While double layer formation has remained an active area of research for more than a century, most frameworks used to predict electric double layer properties, such as local ion concentrations, potential gradients, and reactant chemical potentials, remain rooted in classical Gouy-Chapman-Stern theory, which neglects ion-ion interactions and assumes non-reactive interfaces. Yet, recent findings from the surface forces and electrocatalysis communities have highlighted how the emergence of ion-ion interactions fundamentally alters electric double layer formation mechanisms and interface properties. Notably, recent studies with ionic liquids show that ionic correlations and clustering can substantially alter reaction rates and selectivity, especially in concentrated electrolytes. Further, emerging studies suggest that electric double layer structures and dynamics significantly change at potentials where electrocatalytic reactions occur. Here, we provide our perspective on how ion-ion interactions can impact electric double layer properties and contribute to modulating electrocatalytic systems, especially under conditions where high ion concentrations and large applied potentials cause deviations from classical electrolyte theory. We also summarize growing questions and opportunities to further explore how electrochemical reactions can drastically alter electric double layer properties. We conclude with a perspective on how these findings open the door to using electrocatalytic reactions to study electric double layer formation and achieve electrochemical conversion by engineering electrode-electrolyte interfaces.
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Thermodynamic and kinetic modeling of electrocatalytic reactions using a first-principles approach
The computational modeling of electrochemical interfaces and their applications in electrocatalysis has attracted great attention in recent years. While tremendous progress has been made in this area, however, the accurate atomistic descriptions at the electrode/electrolyte interfaces remain a great challenge. The Computational Hydrogen Electrode (CHE) method and continuum modeling of the solvent and electrolyte interactions form the basis for most of these methodological developments. Several posterior corrections have been added to the CHE method to improve its accuracy and widen its applications. The most recently developed grand canonical potential approaches with the embedded diffuse layer models have shown considerable improvement in defining interfacial interactions at electrode/electrolyte interfaces over the state-of-the-art computational models for electrocatalysis. In this Review, we present an overview of these different computational models developed over the years to quantitatively probe the thermodynamics and kinetics of electrochemical reactions in the presence of an electrified catalyst surface under various electrochemical environments. We begin our discussion by giving a brief picture of the different continuum solvation approaches, implemented within the ab initio method to effectively model the solvent and electrolyte interactions. Next, we present the thermodynamic and kinetic modeling approaches to determine the activity and stability of the electrocatalysts. A few applications to these approaches are also discussed. We conclude by giving an outlook on the different machine learning models that have been integrated with the thermodynamic approaches to improve their efficiency and widen their applicability.
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- Award ID(s):
- 2306929
- PAR ID:
- 10493549
- Publisher / Repository:
- AIP Publishing
- Date Published:
- Journal Name:
- The Journal of Chemical Physics
- Volume:
- 159
- Issue:
- 11
- ISSN:
- 0021-9606
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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