Electrode Materials and Their Electrochemical Behavior

Electrode Materials and Their Electrochemical Behavior. There is abundant evidence that the rate of electron transfer across an electrode-solution interface is dependent on the physical and chemical properties of the electrode material. The term electrocatalysis has been coined for this effect, and studies of the oxidation of hydrocarbons61 and the reduction of water and hydronium ion62 have provided ample evidence for its existence. 

TABLE 5.5 The Exchange Current Density y0 for the Hydrogen Evolution Reaction in 1 M H2S04 

Electrode reactions are analogous to any heterogeneous chemical reaction where reaction takes place on a catalytic surface, with one important difference.37 The heterogeneous chemical reaction does not involve a net charge transfer across the interface and is potential independent, while the electrode reaction involves a net charge transfer across the interface, and therefore the reaction rate is potential-dependent. In effect, the activation energy of the electrode reaction can be controlled by varying the potential. 

The net current density, described by the Buther-Volmer equation [see Chapter 1, Eq. (1.61)] 

The most commonly used electrode materials are mercury various forms of carbon, gold, platinum, and other noble metals carbide, borides and conducting tin oxide films on glass. 

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