What Is a Sound Activated Cathode?

Activation polarization refers to the phenomenon that the potential of an electrode deviates from its equilibrium potential due to the delayed electrochemical reaction of the electrode. Also called electrochemical polarization or chemical polarization, it is a basic form of electrode polarization. Activated polarization is prone to occur at low current densities. Anode activation polarization means that it is difficult for the electro-oxidation reaction on the anode to release electrons. To promote the release of electrons, the anode potential must be corrected to the equilibrium potential. Cathodic activation polarization is that it is difficult for the electroreduction reaction on the cathode to absorb electrons. In order to promote electron absorption, the cathode potential must be made more negative than the equilibrium potential.

Activation polarization refers to the electrode's electrochemical reaction caused by the delay

Under irreversible conditions, when a current is passed through the electrode, an irreversible electrode reaction occurs, and the electrode potential at this time is different from the reversible electrode potential. The phenomenon that the electrode potential exhibits a deviation from the reversible electrode potential when a current passes through it is called electrode polarization. The characteristics of electrode polarization are: the cathode potential is more negative than the equilibrium potential (cathode polarization), and the anode potential is more positive than the equilibrium potential (anodic polarization) ^[1]

(1) Anode activation polarization

Anode activation polarization means that it is difficult for the electro-oxidation reaction on the anode to release electrons. To promote the release of electrons, the anode potential must be corrected to the equilibrium potential.

(2) Cathodic activation polarization

Cathodic activation polarization is that it is difficult for the electroreduction reaction on the cathode to absorb electrons. In order to promote the absorption of electrons, the cathode potential must be made more negative than the equilibrium potential.

The theory about activation polarization is not mature enough. It is generally believed that activation polarization is related to the activation energy of one of the slowest steps in the electrode process consisting of a series of continuous steps. This step requires a higher activation energy to activate the particles participating in the electrode reaction and complete the transfer of electrons. This new external energy is provided by the activated polarization of the electrode ^[2]

The most important factors affecting the activation polarization are the current density and the electrode material, regardless of the agitation.

Activated polarization mainly occurs in the electrode process with gas products (especially H ₂ and O ₂ ), and its effects on electrolysis have advantages and disadvantages, which need to be analyzed in detail ^[3] .