Steady state performance of copper impregnated Ni/PTFE gas diffusion electrode in alkaline fuel cell

The steady-state polarization measurements on a Raney nickel gas diffusion electrode impregnated with copper oxide were carried out in a half-cell setup with 25% KOH electrolyte solution. Pure hydrogen gas was used at a pressure of 1.2 bars in the temperature range of 25-75 degrees C. The results were compared with almost the same electrode without copper. There was an improvement in the performance of the electrode impregnated with about 8 wt% Cu. This improvement is much more pronounced at higher temperatures and higher current densities. The spherical Raney catalyst grain model was used to determine the kinetic parameters such as exchange current density (i(0)) and charge transfer coefficient (alpha) for the electrode. The values found for the exchange current densities at various temperatures were 6.6 x 10(-6)-3.1 x 10(-4) mA cm(-2) and for the charge transfer coefficient was about 0.6. The exchange current density followed an exponential relation with temperature. The apparent activation energy for the electrode reaction at zero mV overvoltage was found to be lower (28 kJ mol(-1)) than that reported in the literature (32 kJ mol(-1)). The higher values for the exchange current densities and lower values for the activation energies are indication of better performance of the electrode used in this study. Copyright (C) 1996 International Association for Hydrogen Energy.