Hermann, V
(Institute of Chemical Engineering, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland)
,
Dutriat, D
(Institute of Chemical Engineering, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland)
,
Müller, S
(Paul Scherrer Institute, Electrochemistry, CH-5232 VilligenPSI, Switzerland)
,
Comninellis, Ch
(Institute of Chemical Engineering, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland)
AbstractThe mechanism of the oxygen reduction reaction (orr) was studied in alkaline media at La0.6Ca0.4CoO3-activated carbon electrodes in a channel flow cell (CFC). The electrodes were made by depositing a mixture of the perovskite (La0.6Ca0.4CoO3) powder as the catalyst, Vulcan XC 72 as the carbo...
AbstractThe mechanism of the oxygen reduction reaction (orr) was studied in alkaline media at La0.6Ca0.4CoO3-activated carbon electrodes in a channel flow cell (CFC). The electrodes were made by depositing a mixture of the perovskite (La0.6Ca0.4CoO3) powder as the catalyst, Vulcan XC 72 as the carbon, and Triton X-100 as the binder on Ti substrates. The collection efficiency, N, of the double-electrode system in the CFC was evaluated in advance using the ferro–ferricyanide couple. The results obtained for the orr show that the mean number of electrons transferred per O2 molecule, ng, remains around 2, while the ratio k1/k2 (the rate constants for direct reduction to OH− and indirect reduction to HO2−) is much smaller than 1, both at nonactivated and perovskite-activated carbon electrodes. This indicates that most of the oxygen was reduced via the two-electron pathway to HO2−. The hydrogen peroxide ions appear to be stable at Vulcan, but are further reduced and/or chemically decomposed in part in the presence of the metal-oxide catalyst.
AbstractThe mechanism of the oxygen reduction reaction (orr) was studied in alkaline media at La0.6Ca0.4CoO3-activated carbon electrodes in a channel flow cell (CFC). The electrodes were made by depositing a mixture of the perovskite (La0.6Ca0.4CoO3) powder as the catalyst, Vulcan XC 72 as the carbon, and Triton X-100 as the binder on Ti substrates. The collection efficiency, N, of the double-electrode system in the CFC was evaluated in advance using the ferro–ferricyanide couple. The results obtained for the orr show that the mean number of electrons transferred per O2 molecule, ng, remains around 2, while the ratio k1/k2 (the rate constants for direct reduction to OH− and indirect reduction to HO2−) is much smaller than 1, both at nonactivated and perovskite-activated carbon electrodes. This indicates that most of the oxygen was reduced via the two-electron pathway to HO2−. The hydrogen peroxide ions appear to be stable at Vulcan, but are further reduced and/or chemically decomposed in part in the presence of the metal-oxide catalyst.
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