Carbon nanofiber-based active layers for fuel cell cathodes - preparation and characterization

Cathodes with silver and platinum as catalysts supported on carbon nanofibers for the oxygen reduction reaction were investigated with an alkaline electrolyte. Nowadays, alkaline fuel cells serve again as an interesting alternative to polymer electrolyte fuel cells, due to the fact that silver can be used as catalyst for the oxygen reduction reaction. The investigated electrodes are prepared by a rolling process and consist of an active layer, prepared of carbon nanofibers as catalyst support and polytetrafluorethylene (PTFE) connected onto a gas diffusion electrode (GDE). The electrodes were electrochemically investigated by measuring polarization curves. It is shown that, together with a certain PTFE content, the fibers are capable of providing the required porosity and pore structure, as well as an excellent electrical conductivity in order to be used as material for GDE production. The measurements are carried out in half cell tests at 80 °C with 9 M KOH as electrolyte. In addition, carbon nanofibers and electrodes were physically characterized by scanning electron microscopy.