Investigation of non-platinum cathode catalysts for direct borohydride fuel cells

Non-platinum electrocatalysts, i.e. iron tetramethoxyphenyl porphyrin (FeTMPP), silver and nickel, were evaluated regarding their ORR performances in alkaline media in half-cells and in alkaline electrolyte borohydride fuel cells. The FeTMPP cathode showed superior performances to those observed using the silver and nickel cathodes, e.g. a current density of −32.2 mA cm−2 at −0.8 V vs. Hg/HgO, an exchange current density of 7.3 × 10−8 mA cm−2 and power densities of up to 65.3 mW cm−2. The difference in performance can be attributed to variations in activity towards oxygen reduction reaction and in borohydride tolerance among the cathodes. The non-platinum cathodes were compared to a platinum cathode.