ELECTROCHEMISTRY OF TIN IN 6 M KOH SOLUTION

Cyclic polarization of TiN electrodes in 6 M KOH at room temperature r evealed relatively large anodic and cathodic overpotentials for water decomposition that depend on the surface structure of the material. Po lished TiN electrodes also underwent a slow reaction during anodic pol arization above the reversible potential for O-2 evolution that involv ed the formation of a reaction product film. The film was uniform over the surface of the electrodes and contained hydrous potassium titanat e. A corrosion product, similar in composition but less uniform in app earance, formed on TiN after 4 months under open-circuit conditions in the same solution. Results indicate that the film forms slowly by a d issolution/precipitation mechanism and that the dissolution step gives rise to an oxidation peak observed in the cyclic voltammogram during anodic polarization. Since the film forms above the reversible potenti al for O-2 evolution and since the overvoltage for O-2 evolution depen ds on surface structure, it is not yet clear whether the formation of the corrosion film will compete with electrolysis reactions during the charging of structurally tailored, high surface area, TiN electrodes that are under development for ultracapacitor applications.