Diffusion and Kinetic Controlled Electrochemical Reactions

An electrochemical reaction on the surface of an electrode can occur by two limiting mechanisms: the reaction is controlled by kinetics and the reaction is controlled by the diffusion of the electroactive species. When the diffusion of the species is infinitely fast, the phenomenon is controlled by kinetics. When the kinetics are extremely fast, the phenomenon is controlled by the diffusion (mass transport) of the species that enters or leaves the electrode surface. This Demonstration shows the current on the left (blue) when controlled by kinetics and on the right (red) when controlled by diffusion.