1. Electron‐Transfer Reactions on Passive Chromium
- Author
-
Fu-Ren F. Fan, Hongjun Yang, Thomas P. Moffat, and Allen J. Bard
- Subjects
Passivation ,Renewable Energy, Sustainability and the Environment ,Kinetics ,Analytical chemistry ,chemistry.chemical_element ,Condensed Matter Physics ,Redox ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Overlayer ,Chemical kinetics ,Chromium ,Electron transfer ,chemistry ,Materials Chemistry ,Electrochemistry ,Outer sphere electron transfer - Abstract
The kinetics of electron transfer between electrochemically passivated chromium and several outer-sphere redox couples have been investigated as a function of passive-film thickness, d = 5 to 25/~, in 1M H2SO4. The apparent rate of electron transfer decreased exponentially with increasing thickness of the passivating overlayer. Similarly, during potentiostatic film growth, the electron-transfer rate decreased logarithmically with time, t, as a consequence of'the film-growth kinetics, since d varies with log(t). These relationships indicate an electron-tunneling controlled process. However, variations in the film thickness and defects result in electron transfer occurring at distributed sites of enhanced tunneling probability, making a meaningful quantitative analysis difficult.
- Published
- 1992