ausblenden:
Schlagwörter:
-
Zusammenfassung:
The electrocatalytic oxidation of small organic molecules is of general importance for energy-related issues such as the fuel cells and electrochemical re-formation. The common emergence of current/potential oscillations in these reactions has implications on mechanistic aspects as well as on the overall conversion, and thus on the performance of practical devices. We investigate in this paper some general features of the electro-oxidation of formaldehyde, formic acid, methanol, and ethanol on platinum and in acidic media, with emphasis on the comparison of the activity under conventional and oscillatory regimes. The comparison is carried out by different means and generalized by the use of identical experimental conditions in all cases. In all four systems studied, the occurrence of potential oscillations is associated with excursions of the electrode potentials to lower values, which noticeably decreases the overpotential of the anodic reaction, when compared to that in the absence of oscillations. Quantitatively speaking, a 2-fold enhancement in the power density was observed in an idealized fuel cell operated with formaldehyde. This aspect, together with spontaneous self-cleaning processes, presents important advantages to the use of autonomous oscillations to reach both higher and long-term activities. Finally, some mechanistic aspects of the studied reactions are also discussed.
