Inhibiting Unwanted Redox Reactions with Valve Metal Oxide Topcoats on Dimensionally Stable Anodes

It has been recently discovered that the application of valve metal oxide topcoats to dimensionally stable anodes can inhibit redox reactions. Typically, tantalum oxide is coated over an existing IrO2-Ta2O5 coating using a thermal decomposition method. It is believed that the tantalum oxide topcoat produces a porous barrier that inhibits reactants from reaching the electrocatalytic surface of the IrO2-Ta2O5 while allowing water to pass at a rate sufficient to maintain electrolysis. The inhibiting effect has been shown on both a laboratory and commercial scale for reactions such as ferrous oxidation, chloride oxidation, destruction of organic brightener and the deposition of manganese dioxide.