ELECTRICAL DOUBLE LAYER

"The structure of charge accumulation and charge separation that always occurs at the interface when an electrode is immersed into an electrolyte solution. (For a simple example see equilibrium electrode potential.) The excess charge on the electrode surface is compensated by an accumulation of excess ions of the opposite charge in the solution. The amount of charge is a function of the electrode potential. This structure behaves essentially as a capacitor. There are several theoretical models that describe the structure of the double layer. The three most commonly used ones are the Helmholtz model, the Gouy-Chapman model, and the Gouy-Chapman-Stern model. "