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Lecture

Electric Double Layer: Theory and Modelling

In course

CH-341: Physical chemistry of interfaces

Acquire an understanding of interfacial phenomena, micro-heterogeneous colloidal solution systems and dynamic electrochemistry. ...

Description

This lecture covers the concept of the electric double layer (DL) around charged surfaces in solution, including the Helmholtz model, Gouy-Chapman model, and Stern model. It explains the formation of the DL, the role of counterions, and the differences between the static and diffuse layers.

Instructor

Rainer Beck

Professor titulaire EPFL, 2006 Privat Docent EPFL, 1997 Habilitation and venia legendi, Universität Karlsruhe, 1996 Ph.D. in Physical Chemistry, Oregon State University, 1990 Degree in Physics, Universität Stuttgart, 1985

Official source

Related concepts (14)

Double layer (surface science)

In surface science, a double layer (DL, also called an electrical double layer, EDL) is a structure that appears on the surface of an object when it is exposed to a fluid. The object might be a solid particle, a gas bubble, a liquid droplet, or a porous body. The DL refers to two parallel layers of charge surrounding the object. The first layer, the surface charge (either positive or negative), consists of ions which are adsorbed onto the object due to chemical interactions.

Surface charge

A surface charge is an electric charge present on a two-dimensional surface. These electric charges are constrained on this 2-D surface, and surface charge density, measured in coulombs per square meter (C•m−2), is used to describe the charge distribution on the surface. The electric potential is continuous across a surface charge and the electric field is discontinuous, but not infinite; this is unless the surface charge consists of a dipole layer. In comparison, the potential and electric field both diverge at any point charge or linear charge.

Debye length

In plasmas and electrolytes, the Debye length (Debye radius or Debye–Hückel screening length), is a measure of a charge carrier's net electrostatic effect in a solution and how far its electrostatic effect persists. With each Debye length the charges are increasingly electrically screened and the electric potential decreases in magnitude by 1/e. A Debye sphere is a volume whose radius is the Debye length. Debye length is an important parameter in plasma physics, electrolytes, and colloids (DLVO theory).

Zeta potential

Zeta potential is the electrical potential at the slipping plane. This plane is the interface which separates mobile fluid from fluid that remains attached to the surface. Zeta potential is a scientific term for electrokinetic potential in colloidal dispersions. In the colloidal chemistry literature, it is usually denoted using the Greek letter zeta (ζ), hence ζ-potential. The usual units are volts (V) or, more commonly, millivolts (mV).

Electric vehicle

An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes charged by solar panels, or by converting fuel to electricity using fuel cells or a generator). EVs include, but are not limited to, road and rail vehicles, surface and underwater vessels, electric aircraft, and electric spacecraft.

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Explains the electric double layer on charged surfaces in solution, focusing on the Helmholtz model and its limitations.

Electrokinetic Phenomena: Double Layer and Flow Dynamics

Explores electrokinetic phenomena, including colloidal particle motion and the diffuse double layer model in chemical separations.

Colloid Stability: DLVO Theory and Membrane Potential

Explores the DLVO theory and membrane potential to understand colloid stability and forces between charged surfaces.

Colloids: Particle Motion and Stabilization

Explores colloids, particle motion, stabilization forces, and sedimentation speed, including electrostatic and steric stabilization, colloidal dispersions, and zeta potential measurements.

Interfacial Chemistry: Surface Tension, Adsorption, Electrokinetics