A comprehensive study of the kinetics of hydrogen peroxide reduction reaction by rotating disk electrode

This work presents a methodology to analyze hydrogen peroxide reduction reaction (HPRR) studied by rotating disk electrode (ROE). Generally the Koutecky-Levich equation is used to determine the kinetic parameters of an electrochemical reaction. This equation is not applicable to electrochemical reactions with a complex reaction mechanism. The HPRR is an example of these complex reactions because the H2O2 reduction, H2O2 decomposition and O-2 reduction may take place simultaneously on the electrode surface. In the current work the mass transport equations of H2O2 in the electrolyte and the reaction equations on the electrode surface are solved simultaneously under the steady state conditions to derive a specific equation for HPRR. The new equation shows the same linear relationship between the inverse of the current density (j(-1)) and the inverse square root of the rotation frequency (omega(-1/2)), but the slopes and the intercepts of the lines are shown to be functions of the reaction rate constants involved in the HPRR. One of the most important results of the work is the possibility to determine the hydrogen peroxide decomposition rate constant directly from RDE data. Prediction of simultaneous reduction of H2O2 and O-2 on the electrode and suggestion a mechanism for HPRR are other advantages of the derived equation when compared with Koutecky-Levich equation. (C) 2013 Elsevier Ltd. All rights reserved.