Water distribution at the electrified interface of deep eutectic solvents.

Area of Science:

• Electrochemistry
• Materials Science
• Physical Chemistry

Background:

• Deep eutectic solvents (DESs) offer a wider potential window and high electrochemical stability compared to water.
• The inherent hygroscopic nature of DESs leads to unavoidable residual water, impacting their electrochemical performance.
• Understanding water's behavior at electrified interfaces is crucial for optimizing DES applications.

Purpose of the Study:

• To investigate the interfacial structure and water distribution in choline chloride-urea DES (Reline) at an electrified graphene interface.
• To explore the electrosorption and distribution of varying water concentrations within the DES.
• To elucidate the influence of electrode electrification on water behavior.

Main Methods:

• Atomistic molecular dynamics simulations were employed.
• The study focused on the Reline (1:2 choline chloride-urea) DES at a graphene electrode interface.
• Simulations analyzed systems with different amounts of residual water.

Main Results:

• Water distribution and interfacial structure are sensitive to the graphene electrode's electrification.
• For moderately charged electrodes, water exhibits preferential asymmetric adsorption near the positively charged electrode via hydrogen bonding with anions.
• At highly charged electrodes, water adsorbs to both electrodes due to enhanced electrostatic interactions with water dipoles.

Conclusions:

• Electrode charge significantly dictates water's interfacial behavior in DESs.
• Hydrogen bonding and electrostatic interactions govern water's distribution and electrosorption.
• These findings are vital for designing and utilizing DES-based electrochemical systems effectively.