In-plane structure of the electric double layer in the primitive model using classical density functional theory

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Chemistry

Background:

• The electric double layer (EDL) plays a crucial role in charge screening at interfaces, impacting supercapacitors and colloidal systems.
• EDL structure is dictated by correlations among finite-sized ions, influencing overall system properties.

Purpose of the Study:

• To investigate if EDL structural transitions, driven by surface potential, are universal or specific to ion interactions.
• To explore the in-plane structure of EDLs using classical density functional theory (DFT).

Main Methods:

• Utilizing classical density functional theory (DFT) with an appropriate functional.
• Comparing DFT predictions with molecular dynamics simulations for validation.
• Analyzing the EDL structure factor parallel to a charged surface.

Main Results:

• An appropriate DFT functional accurately predicts the in-plane EDL structure, matching molecular dynamics simulations.
• The study mapped the EDL structure within the primitive model for various electrostatic potentials.
• No evidence of a fundamental structural crossover was found.

Conclusions:

• Previously reported EDL structural transitions are likely artifacts of specific ion force fields, not fundamental properties.
• The developed DFT approach provides a reliable platform for studying EDL in-plane structures.