The electrochemistry of silver in KOH at elevated temperatures—IV. AC impedance study

✍ Scribed by Bruce G. Pound; Digby D. MacDonald; John W. Tomlinson

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 906 KB
• Volume: 27
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(82)80044-3

✦ Synopsis

The (~c impedance properties of silver in 1 mol kg-' KOH were studied under potentiostatic conditious over the temperature range 295-478 K. Measurements were obtained over the frequency range 0.5 Hz-5 kHz, and were analyzed in terms of equivalent circuits. It was shown that provision for surface roughness is required for a satisfactory explanation of the impedance data. Values for the double layer capacity and the concentration of AgO-ions at the electrode surface could generally then be obtained. At potentials corresponding to the formation of Ag,O, it is demonstrated that both diffusion in solution and diffusion in the oxide film are operative. At elevated temperatures, the rate of growth of Ag,O centres is controlled partly by diffusion in the oxide and partly by a reaction step at the growing interfaces of the centers. The subsequent formation of Ag,O,, at all temperatures in the range studied, is interpreted on the basis of an electrocrystallisation impedance.