Charge transfer reactions on oxide-covered Ti Electrodes: Effect of dielectric constant variation and oxide stabilization
✍ Scribed by Dr. M. A. Abdel Rahim; Dr. Amal A. Abdel Rahman; Dr. M. W. Khalil
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 507 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0933-5137
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✦ Synopsis
Abstract
The electron transfer kinetics of the Fe^3+^/Fe^2+^ redox couple on the oxide covered Ti electrodes were investigated as a function of the film thickness, film stabilization, and concentration of the redox species. The oxides were formed potentiodynamically in acidic solution of pH=3 (Na~2~SO~4~+H~2~SO~4~) at a scan rate of 1 mV s^−1^. The cathodic and anodic Tafel lines were also measured at the same scan rate.
The logarithm of the exchange current density i~0~ shows an exponential decrease with the oxide film thickness. Direct tunnelling may explain the kinetics of the reaction across thin Ti0~2~ (oxide formed at the potential region before the O~2~‐evolution). Values of the cathodic and anodic transfer coefficients are tabulated. It was found that, the stabilization of the oxide could possibly increase its conductivity. The electron transfer reaction showed a first order dependence on the redox species concentration, independent of the conditions of oxide film formation.