Capacitance of electrolytes with hydration-mediated interaction in planar electric double layers

• Published in: Molecular physics 2020-02, Vol.118 (3), p.e1610196
• Main Authors: Heo, Minhye, Shin, Ghi Ryang, Kim, Soon-Chul
• Format: Article
• Language: English
• Subjects: Anions; Capacitance; Charge density; Computer simulation; density functional approach; differential capacitance; Electrolytes; Hydration; Hydration-mediated potential; Surface charge
• ISSN: 0026-8976; 1362-3028
• DOI: 10.1080/00268976.2019.1610196

The theoretical model, which is based on the density functional approach, has been developed for studying the electrostatic properties of electrolytes with the soft, hydration-mediated ion-ion and ion-surface interactions. The theory approximates the hydration-mediated ion-ion interaction through the mean-field approximation. The results show that the theory leads to a good agreement with the simulation results and predicts the camel-to-bell shape transition for the charged hard-core Yukawa ions with the hydration-mediated interaction. The high is observed at a low bulk concentration of ions and the camel-to-bell shape transition occurs when the bulk concentration rises to an appropriate value. The increase of an ion size shifts the maximum differential capacitance ( ) to a low surface charge density. The addition of a repulsive hydration interaction reduces the , whereas the attractive hydration interaction enhances the . The increase of ion-surface and ion-ion interactions decreases the and shifts the maximum to a higher surface charge density. The increase of hydration anion-anion repulsion decreases the of a positively charged electrode and shifts its maximum to more positively charged surfaces.