| Autor: |
NEVENKA R. ELEZOVIC, BILJANA M. BABIC, NEDELJKO V. KRSTAJIC, SNEZANA LJ. GOJKOVIC, LJILJANA M. VRACAR |
| Jazyk: |
angličtina |
| Rok vydání: |
2008 |
| Předmět: |
|
| Zdroj: |
Journal of the Serbian Chemical Society, Vol 73, Iss 6, Pp 641-654 (2008) |
| Druh dokumentu: |
article |
| ISSN: |
0352-5139 |
| Popis: |
The temperature dependence of oxygen reduction reaction (ORR) was studied on highly dispersed Pt nanoparticles supported on a carbon cryogel. The specific surface area of the support was 517 m2 g-1, the Pt particles diameter was about 2.7 nm and the loading of the catalyst was 20 wt. %. The kinetics of the ORR at the Pt/C electrode was examined in 0.50 mol dm-3 HClO4 solution in the temperature range from 274 to 318 K. At all temperatures, two distinct E–log j regions were observed; at low current densities with a slope of –2.3RT/F and at high current densities with a slope of –2.3´2RT/F. In order to confirm the mechanism of oxygen reduction previously suggested at a polycrystalline Pt and a Pt/Ebonex nanostructured electrode, the apparent enthalpies of activation at selected potentials vs. the reversible hydrogen electrode were calculated in both current density regions. Although ∆Ha,1≠ > ∆Ha,h≠, it was found that the enthalpies of activation at the zero Galvani potential difference were the same and hence it could be concluded that the rate-determining step of the ORR was the same in both current density regions. The synthesized Pt/C catalyst showed a small enhancement in the catalytic activity for ORR in comparison to the polycrystalline Pt, but no change in the mechanism of the reaction. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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