Ion Adsorption at Surfaces from Local and Global Electroneutrality Constraints

Area of Science:

• Physical Chemistry
• Surface Science
• Electrochemistry

Background:

• Ion adsorption at interfaces is crucial for many chemical and physical processes.
• Existing methods for mixed electrolytes lack precision in determining individual ion thermodynamic adsorption.
• Thermodynamic information on relative surface adsorption of individual ions is limited.

Purpose of the Study:

• To develop an exact thermodynamic approach for quantifying individual ion adsorption from mixed electrolyte solutions.
• To provide a method applicable to any number of ions, concentrations, and surface types.
• To enable extraction of detailed surface adsorption information from experimental data.

Main Methods:

• Utilizing local and global electroneutrality principles applied to surface-ion distributions.
• Decomposing surface-ion distribution integrals into charge neutralization and thermodynamic contributions.
• Validating the derived relationships using all-atom explicit solvent molecular dynamics simulations.

Main Results:

• Developed exact surface-ion integral relationships for mixed electrolytes.
• Demonstrated how additional electrolytes influence target ion surface distribution.
• Confirmed the approach's validity and applicability through molecular dynamics simulations.
• Successfully extracted enhanced information from experimental data for vacuum electrolyte solution interfaces.

Conclusions:

• The new method provides exact thermodynamic information on individual ion adsorption without approximations.
• The approach is versatile, applicable to various electrolyte compositions and surface types.
• Enables more detailed analysis of experimental data than previously possible, advancing surface science and physical chemistry.