Constant-Potential Modeling of Electrical Double Layers Accounting for Electron Spillover

Area of Science:

• Computational chemistry and physics
• Materials science
• Electrochemistry

Background:

• Constant-potential molecular dynamics (MD) simulations are crucial for studying electrical double layers (EDLs) at the atomistic level.
• Classical methods underestimate EDL capacitance by neglecting quantum effects like electron spillover.

Purpose of the Study:

• To develop and validate a novel constant potential MD method that incorporates quantum mechanical electron spillover.
• To accurately simulate EDL structure, capacitance, and dynamics at metal-electrolyte interfaces.

Main Methods:

• Developed a modified constant potential MD approach accounting for electron spillover on electrode surfaces.
• Performed simulations for electrical double layers at Au(111) electrodes and aqueous electrolytes.

Main Results:

• The new method yields bell-shaped EDL capacitance curves quantitatively matching experimental results for Au(111) electrodes.
• Simulations reveal electrode-polarization-dependent local electric fields, explaining observed vibrational redshifts and predicting blueshifts in interfacial water.
• Identified geometry-dependent charging timescales.

Conclusions:

• The proposed constant potential MD method accurately captures quantum effects, improving EDL simulations.
• This approach provides a more realistic understanding of interfacial phenomena in electrochemical systems.
• The findings offer new insights into the behavior of water at electrode surfaces under varying polarization.