Mixed Metal Oxide Coating for the Electrochemical Process

Mixed Metal Oxide Coating for the Electrochemical Process

Mixed metal oxide coatings on titanium plates are widely used as anodes in a variety of electrochemical processes like chlorine generation in the Chlor-alkali industry, oxygen production, electrowinning of metals, and cathodic protection. Noble metal oxides such as RuO2 and IrO2 with high conductivity and electrochemical activity have received considerable attention in the electrochemical industry as electro-catalyst.

For further improvement instability of these oxides, other oxides like TiO2, Ta2O5, and ZrO2 are added to these active oxides. Anodic evolution of chlorine and oxygen is the most important reaction in the application of these materials. Oxygen evolution reaction is the most important reaction in some electrochemical processes such as water electrolysis, metal electrowinning, and cathodic protection. In addition, this reaction is an unavoidable reaction that can proceed in many anodic processes. RuO2 based coatings like pure RuO2 and RuO2–TiO2 are very stable for chlorine evolution reaction. However, they are unstable for anodic oxygen evolution reaction and undergo heavy corrosion in acidic media. IrO2 is more stable for oxygen evolution reaction but it has a lower electro-catalytic activity for oxygen evolution. Thus mixed compounds of IrO2 and RuO2 can be an appropriate electrocatalyst for oxygen revolution due to the advantageous properties of both oxides.

Mixing two or more different oxides can influence the electrocatalytic properties of oxides by changing the microstructure, surface composition, and morphology of electrocatalyst components. In addition, the surface composition, morphology, and microstructure of mixed oxide coatings are not homogenous and can be influenced by preparation factors and amounts of active oxides.