dubbellag

Dubbellag, or the electrical double layer, is the structure of charge that forms at the interface between a conductive solid, such as an electrode, and an electrolyte solution. When the solid surface acquires or presents charge, counter-ions in the solution accumulate near the surface, creating a layer of charge on the solid and a balancing layer of ions in the liquid. Together, these layers establish a potential difference across the interface.

Historically, models of the double layer range from a simple Helmholtz picture, in which all charge resides in a compact layer right at the surface, to more refined descriptions that include a diffuse layer of ions governed by electrostatic screening. The most widely used modern framework combines a compact, near-surface layer with a diffuse layer (Gouy–Chapman–Stern model). This approach accounts for finite ion size and the gradual decay of potential with distance from the surface.

The double layer is typically only a few nanometers thick, with its properties depending on the electrode material, the electrolyte composition, and the ionic strength. Its capacitance per area and the Debye length influence the rate and efficiency of electrochemical reactions, energy storage devices, corrosion processes, and sensor performance. In colloid and interface science, the double layer also governs particle stability through the zeta potential, which reflects the electric potential in the diffuse region near a surface.

Dubbellag is a central concept in electrochemistry and interfacial science, linking surface charge, ion distribution, and electrostatic phenomena at interfaces.