| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 186212 | Electrochimica Acta | 2014 | 7 Pages |
•The optimum rotation rate was found to be between 600 rpm and 900 rpm.•The increase of temperature from 25 °C to 60 °C increased the voltage efficiency (ηV) for all the substrates examined.•The majority of the coatings examined lost some of their activity on prolonged cycling (150 cycles).•The substrates containing higher Pt coatings (optimum 10 g m−2) showed higher ηV values and cycling stability.•The current densities that could be applied on the substrates tested were not greater than 25 mA cm−2.
In this study, the charge/discharge cycling behaviour of the Ce3+/Ce4+ redox couple in methanesulfonic acid medium on various Pt and Pt-Ir coated titania based substrates was investigated as a function of solution flow rate, temperature and charge/discharge current density using a rotating disk electrode. Although superior performances (in terms of the voltage efficiency, ηV) were obtained from the electrodes containing higher amounts of platinum, a deterioration of these electrodes with cycling was evident (after 150 cycles). At rotation rates between 600 rpm and 1200 rpm, high ηV (>90%) could be obtained as long as the current density j applied was below the mass transport limiting current density, jL. For j's above this value, the oxygen evolution reaction occurred with Ce3+ oxidation whereas the Ce4+ reduction was accompanied by oxygen reduction, resulting in lowered ηV's. Better stability towards cycling and higher ηV's were observed at 60 °C compared to 25 °C, especially for the etched Pt electrodes. The optimum loading for the Pt substrates was 3 g m−2 while for the case of the heat treated samples 10 g m−2 of Pt.
