Temperature dependence of the kinetics of oxygen reduction on carbon-supported Pt nanoparticles
AuthorsElezovic, Nevenka R.
Babić, Biljana M.
Krstajic, Nedeljko V.
Gojković, Snežana Lj.
Vracar, Ljiljana M.
MetadataShow full item record
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 5 17 m(2) 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 x 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 Delta H-a,l(not equal) GT Delta H-a,h(not equal), it was found that the enthalpies of activation a...t 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.
Keywords:oxygen reduction reaction / platinum catalyst / carbon support / temperature dependence / enthalpy of activation
Source:Journal of the Serbian Chemical Society, 2008, 73, 6, 641-654
- Ministry of Science of the Republic of Serbia