How Mixed Metal Oxide Coated Titanium Anodes Applied in Electrochemical Industry?

How Mixed Metal Oxide Coated Titanium Anodes Applied in Electrochemical Industry?

Titanium based mixed metal oxide anodes have played an important role in the electrochemical industry. They are essentially mixed metal oxide films deposited on titanium and have been used to replace the conventional graphite electrodes. With long service life and allowing higher current densities, they are named“dimensionally stable anodes” because their material is not consumed during electrolysis, unlike graphite anode.

The mixed metal oxide materials can be categorized as “active” and “non-active”, according to the nature of the anodic interaction with the electrolyte species. Anodes such as ruthenium oxide (RuO2) and iridium oxide (IrO2) are considered active anodes. They are often used in combination with other oxides, particularly TiO2 and Ta2O5, to increase stability and reduce the cost.

The coating composition is mainly from the platinum family, such as platinum, iridium, and ruthenium. These materials are often made as mixed oxides to reduce the number of noble metals within the oxide structure. Ruthenium dioxide, when mixed with titanium dioxide, has been successfully used for chlorine evolution. Iridium oxide was used in combination with tantalum oxide for oxygen evolution.

Most mixed metal oxide coated titanium anodes can be prepared by a generic procedure in which the chloride of the metal is coated onto the pretreated titanium and subsequently calcined in the air.

A common problem of the whole family of titanium based mixed metal oxide anodes is their service life. The main limiting factors of service life reflected in the deactivation of the electrode were postulated to be: erosion, elution of active materials, and the passivation of the titanium substrate, and more than one event might occur simultaneously.