Electrochemical behaviour of a hydrogen/oxygen gas mixture at a solid polymer electrolyte interface

Abstract

The electrochemical behaviour of a hydrogen/oxygen gas mixture at platinum electrodes in contact with a solid polymer electrolyte (Nafion 115) was studied in two modes: hydrogen enrichment and fuel cell. In the hydrogen enrichment (purification) mode, i/V(V being the applied voltage) characteristics were identified for the electrochemical cell arranged so that the gas mixture with varying ratios which contacts the anode was purified to pure hydrogen gas that was released at the cathode. In the fuel cell mode, V/i (V being the terminal voltage) characteristics were determined for the cell which utilized the gas mixture with varying ratio at the anode and pure oxygen at the cathode. The effect of the decrease in the mole fraction of hydrogen (χH2) on the current density or the terminal voltage was particularly severe for χH2<0.6. The drop was analysed employing terms such as oxygen reduction current, oxygen adsorption and the change of e.m.f. (electromotive force) due to the decrease in the partial pressure of the hydrogen gas.