Continuum models of the electrochemical diffuse layer in electronic-structure calculations.

Area of Science:

• Electrochemistry
• Materials Science
• Computational Chemistry

Background:

• Continuum electrolyte models are used to describe the diffuse layer at electrochemical interfaces.
• Accurate modeling of interface observables like differential capacitance (DC) is crucial but not well-understood.
• Coupling continuum models with atomistic descriptions is key for electrified interfaces.

Purpose of the Study:

• To critically compare continuum diffuse-layer models for electrochemical interfaces.
• To validate model accuracy against experimental differential capacitance data.
• To determine essential features for accurately describing interface observables.

Main Methods:

• Coupling atomistic first-principles calculations with continuum diffuse-layer models.
• Computing differential capacitance for a prototypical Ag(100) surface in aqueous solution.
• Comparing computed DC values to experimental data.

Main Results:

• A size-modified Poisson-Boltzmann model qualitatively reproduces experimental trends for differential capacitance.
• The dielectric cavity parameterization significantly impacts computed DC values.
• Validated accuracy of continuum models for describing electrolyte screening.

Conclusions:

• A size-modified Poisson-Boltzmann approach is sufficient for qualitatively describing electrochemical interface behavior.
• Dielectric cavity parameterization is a critical factor in model accuracy.
• Continuum models, when validated, are practical tools for materials science research.