Oxidation of zinc in alkaline solutions studied by electrochemical impedance spectroscopy
- Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemistry
Electrochemical dissolution and passivation reactions of zinc have been studied in 1.0 M KOH solutions by electrochemical impedance spectroscopy. Equivalent circuits have been worked out by simulating the impedance data and using the results to model the dissolution and passivation reactions. A Tafel plot constructed from the charge-transfer resistances provides an exchange current of 0.11 A/cm{sup 2} and an {alpha} value of 0.36 for zinc oxidation. The maximum rate of zinc oxidation is observed at about {minus}1.30 V vs. the Hg/HgO reference electrode as judged from the charge-transfer resistance minimum obtained from impedance measurements. A negative polarization resistance with a reverse semicircle on the Nyquist plot illustrates the transition process from an active to passive potential region at {minus}1.10 V. At high anodic over-potentials, the zinc electrode behaved as a semiconductor electrode due to a compact ZnO passive film formed on the electrode surface.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 474624
- Journal Information:
- Journal of the Electrochemical Society, Vol. 143, Issue 12; Other Information: PBD: Dec 1996
- Country of Publication:
- United States
- Language:
- English
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