Evans diagram electrochemical systems

Figure 8.3. Evans diagram of current-potential curves for a system with two different simultaneous electrochemical reactions. Kinetic scheme Eqs. (8.4) and (8.5).

Both Evans and Stem diagrams are included in order to compare and analyze simple and uncomplicated electrochemical systems. The concept of anodic control and cathodic control polarization is also introduced. In addition, the predetermined corrosion circuit is included in order to analyze corrosion using an electrochemical device containing an external circuit. 

Electrochemical corrosion systems can be characterized using the kinetic parameters previously described as Tafel slopes, exchange and limiting current densities. However, the mixed potential theory requires a mixed electrode system. This is shown in Eigure 5.1 for the classical pure zinc (Zn) electrode immersed in hydrochloric (NCl)acid solution [1,8-9]. This type of graphical representation of electrode potential and current density is known as Evans Diagram for representing the electrode kinetics of pure zinc. 

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