Kinetic investigation of oxygen reduction reaction in sub-freezing acid media

A three-electrode system with 2 M H(2)SO(4) as the electrolyte was developed to investigate the oxygen reduction kinetics on Pt/C catalyst at sub-freezing temperatures. This system successfully avoided the ice formation above -10 degrees C. Furthermore, the influence of different membrane electrode assembly (MEA) status, i.e. the membrane hydration and the electrode structure, on the kinetic results in a sub-freezing fuel cell was diminished in this method. By cyclic voltammetry (CV) test, the electrochemical active surface area (ECA) of PVC catalyst at sub-freezing temperatures was obtained. Results showed that the ECA at sub-freezing temperatures was almost the same as that at room temperature, either the H-desorption or the H-adsorption process at subzero temperatures still took place in the same way. According to the analysis of the linear scan voltammetry (LSV), the kinetics of oxygen reduction on Pt/C catalyst at sub-freezing temperatures was explored. The limiting current density decreased as temperature dropped and the exchange current density at subzero temperatures still obeyed the Arrhenius theory. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved