Electrocatalytic oxygen reduction reaction on perovskite oxides: series versus direct pathway.
The mechanism of the oxygen reduction reaction (ORR) on LaCoO(3) and La(0.8)Sr(0.2)MnO(3) perovskite oxides is studied in 1 M NaOH by using the rotating ring disc electrode (RRDE) method. By combining experimental studies with kinetic modeling, it was demonstrated that on perovskite, as well as on perovskite/carbon electrodes, the ORR follows a series pathway through the intermediate formation of hydrogen peroxide. The escape of this intermediate from the electrode strongly depends on: 1) The loading of perovskite; high loadings lead to an overall 4 e(-) oxygen reduction due to efficient hydrogen peroxide re-adsorption on the active sites and its further reduction. 2) The addition of carbon to the catalytic layer, which affects both the utilization of the perovskite surface and the production of hydrogen peroxide. 3) The type of oxide; La(0.8)Sr(0.2)MnO(3) displays higher (compared to LaCoO(3)) activity in the reduction of oxygen to hydrogen peroxide and in the reduction/oxidation of the latter.
Institut de Chimie et Procédés pour l'Energie l'Environnement et la Santé, UMR 7515 CNRS-University of Strasbourg, 25 rue Becquerel 67087 Strasbourg Cedex 2 (France), Fax: (+33) 03-68-85-27-61.
Tiphaine
T
Poux
Antoine
A
Bonnefont
Gwénaëlle
G
Kéranguéven
Galina A
GA
Tsirlina
Elena R
ER
Savinova
hydrogen peroxide; kinetic modeling; oxygen reduction reaction; perovskite oxides; rotating ring disc electrode