ON THE FORMATION OF 'AG2O3' ON SILVER ELECTRODES,

Ag2O3 was examined electrochemically in eutectic KOH-H2O at -40C by coulombic measurements of quantities formed, open circuit potential decays, variation of potential as a function of anodic current density, and temperature coefficients of decomposition rates. It can be formed directly from Ag2O on Ag at current density c.d. 15 micro Asq cm, with a maximum thickness during the first oxidation cycle occurring at 65 micro Asq cm. Potential decay curves have protracted linear regions where 0.045 b 0.078, sometimes higher. One-tenth of a layer or adsorbed species superimposed on the higher oxide exists on the surface during O2 evolution. Reduction curves show a minimum in the potential decay of the higher oxide preceding the formation of Ag2O. The Ag2O3 decomposes in approximately 1 h at -40C to either AgO or Ag2O. The activation energy for its thermal decomposition is 12.0 2.0 kcalmole. Under most experimental conditions studied the results indicated that the material is not true Ag2O3 but it is probably better described as Ag2OO where O is trapped oxygen. The evidence does point to the probable existence of a thin layer, which may be true Ag2O3, on the surface in a steady state which is maintained at high anodic current density 100 micro Asq cm at -40C. Author