Journal of Applied Electrochemistry, Vol.28, No.3, 245-250, 1998
Preparation of oxygen evolving electrodes with long service life under extreme conditions
Among the numerous base metals tested for DSA(R) type electrodes (e.g., titanium and its alloys, zirconium, niobium etc.), tantalum is a potentially excellent substrate owing to its good electrical conductivity and corrosion resistance, and the favourable dielectric properties of its oxide. Nevertheless, a DSA(R) type electrode fabricated on a tantalum substrate would be very expensive due to the high cost of the metal. To prepare an anode combining the excellent properties of tantalum at reasonable price, a new material has been developed in our laboratory. This consists of a common base metal (e.g., Cu) covered with a thin tantalum coating. This tantalum layer was obtained by molten salt electroplating in a LiF-NaF-K2TaF7 melt at 800 degrees C. Thus, an anode of the type Metal/Ta/Ta2O5-IrO2 with a surface load of 22 g m(-2) IrO2, submitted to the severe test conditions used in this work, exhibits a standardized lifetime tenfold greater than one made with ASTM grade 4 titanium base metal. Thus, this type of electrode might be advantageously employed as an oxygen evolution anode in acidic solutions.