Temperature-dependence of oxygen reduction activity at a platinum electrode in an acidic electrolyte solution investigated with a channel flow double electrode

Abstract

The temperature dependence of the oxygen reduction reaction (orr) activity at a platinum electrode in 0.1 M HClO 4 electrolyte solution was investigated with a channel flow double electrode at 20–90 °C. We demonstrate that an apparent rate constant ( k app) for the orr can be evaluated from the hydrodynamic voltammograms by correcting the oxygen concentration in the electrolyte solution. The apparent activation energy for the k app was found to be 38 kJ/mol at −0.525 V vs. E 0 (0.760 V vs. RHE at 30 °C). Production of H 2O 2 was not detected at potentials more positive than 0.3 V in the temperature region examined. One capacitive semicircle was observed in electrochemical impedance spectroscopy for the orr, suggesting the fast complete reduction of intermediates to H 2O following the rate determining step of the first electron-transfer.