Reduction of oxygen from electrolyte emulsions with high oxygen contents

The kinetics of oxygen reduction from electrolyte emulsions containing oxygen carriers was studied with respect to fuel cell applications. Electrochemical experiments including stationary and nonstationary measurements under defined hydrodynamic conditions at a rotating platinum disk electrode revealed that diffusion-controlled limiting currents can be increased significantly at high oxygen concentrations. Additionally, the limiting currents show a strong correlation with the composition and the structure of the emulsions. In particular, the average droplet size of the organic phase and its distribution depends on the nature of the emulsifying agents used for stabilisation. The complex hydrodynamic behaviour of two-phase electrolyte emulsions and the influence of different surfactants seem to outweigh the effect of the total oxygen concentration on the transport kinetics of oxygen.