Differential Pulse Volummetry and Stern Double Later

• Electrical double layer is a structure of counter ions that appear on the surface of an object when it is exposed to a fluid. This counter ions are created when a current creating an excess or less negative charge at the surface of two electrode then the ion mobility make the layers of solution to immediately adjust to the electrode acquire a charge of the opposite sign as explained as Helmholts model.

• A double layer refers to two parallel layers of charges surrounding the object with a charged surface and oppositely charged counter ions hat compensating on the surface and which is dependent of the current on the electrode. The concept of an electrical double layer also explains why an electrode can donate or accept electrons only from a species that is present in a solution.

• On a double layer with Gouy-Chaphum model explain diffusion of charge caused by thermic motion of ions, in this model dritribution f ion as a function of distance from the metal surface with electric potential decreasing exponentially away from the surface of the fluid bulk.

• Stern double layer form where fluid near the surface is immobile where ions are also still. Stern suggest some ions adhere to the electrode giving an internal stern layer which accounts for ion closest to the electrode which end up being immobile displayed on a rigid Helmholtz plane.

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• Differential pulse voltammetry is a technique in electrochemistry where a cell current is measured as a function of time and as a function of the potential between the indicator and reference electrodes. The pontential diversified using pulses of increasing amplitude the current is measured immediately before each potential change and after each voltage stage.

• Types of electrode

 Working electrode –is the electrode in an electrochemical system on which the conducted reaction is occurring. Most commonly can be made of inert materials such as Au, Ag, Pt, glassy carbon and Hg drop and film electrodes. The size and shape of the working electrode also differ and it depends on the application. For corrosion applications, the material under investigation like In corrosion testing, the working electrode is a sample of the corroding metal. Generally, it is not the actual metal structure being studied. Instead a small sample is used to represent the structure. The working electrode can be bare metal. The working electrode can be referred to as either cathode or anode.

 Reference electrode-is an electrode which has a stable and well-known electrode potential and it is used as a point of reference in the electrochemical cell for the potential