Image-induced overcharging in the weakly charged surfaces

Electrostatic interactions at dielectric boundaries can bring about novel properties which are vital not only to understand the complex behavior at biological interfaces but also to design desirable interfacial processes for a broad variety of practical applications. Here, we aim to provide comprehensive information by Monte Carlo simulations about the annihilation and formation of the image-induced overcharging effect, a new class of charge accumulation phenomena resulting from an excess of adsorbed ions on the like-charged surfaces. It is observed that whether the image-charge interactions are repulsive or attractive, the buildup of overcharging depends critically on both the concentration and the charge-asymmetry of electrolytes. On the other hand, overcharging is gradually cancelled with an increase in the size of ions and the concentration of monovalent salt as well as in the magnitude of surface charge density. Also, our simulations show that the image-induced overcharging effect cannot promote charge reversal. These findings are especially relevant to colloidal stability and dispersibility, and will hopefully serve as a foundation for the development of adequate theories.