ABSTRACT
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.
GRAPHICAL ABSTRACT
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No potential conflict of interest was reported by the authors.