Thermodynamic cyclic voltammograms: peak positions and shapes

Area of Science:

• Physical Chemistry
• Electrochemistry
• Surface Science

Background:

• Cyclic voltammograms (CVs) are crucial for studying electrochemical interfaces.
• Interface energetics and electrostatic double layer (DL) effects play a significant role in CV behavior.
• Existing interpretations often focus on adsorbate-centered phenomena like electrosorption valency.

Purpose of the Study:

• To analyze the relationship between CV peak characteristics and interface energetics, including DL effects.
• To elucidate the connection between non-Nernstian behavior, DL charging, and adsorbate interactions.
• To provide a framework for analyzing experimental CVs and validating atomistic interface models.

Main Methods:

• Mean-field description of thermodynamic cyclic voltammograms (CVs).
• Analysis of electrostatic double layer (DL) effects on CV peak positions and shapes.
• Case study using Ag(111) in halide-containing solutions.

Main Results:

• DL effects can cause peak shifts, explainable by adsorbate-field interactions.
• Peak shape alterations are primarily driven by coverage-dependent adsorbate dipoles.
• Experimental conditions (ion concentrations) significantly impact CV peaks via DL potential drop and capacitance.

Conclusions:

• DL effects are integral to understanding CVs beyond simple adsorbate energetics.
• Provides a more comprehensive approach to interpreting experimental CV data.
• Offers a method for rigorously assessing the accuracy of theoretical models for electrified interfaces.