Performance of Perovskite-Type Oxides for Oxygen Reduction Reaction in Direct Hydrazine Fuel Cell

Perovskite-type oxide-based La 0.6 Sr 0.4 Mn (1- x ) Co x O 3 /carbon ( x = 0, 0.1, 0.2, 0.3, 1) catalysts were prepared by calcination of a mixture of metal nitrates and PVP at 600 °C, followed by milling of the calcined powder with a carbon support. The catalytic activities for the oxygen reduction reaction (ORR) were tested in alkaline electrolyte by using a rotating ring-disk electrode (RRDE) at 25 °C. With an increase in the doping amount of Co, the onset potential of the La 0.6 Sr 0.4 Mn (1- x ) Co x O 3 /carbon catalyst was found to be shifted in a positive direction and the ring current during ORR decreased. Especially, the La 0.6 Sr 0.4 Mn 0.7 Co 0.3 O 3 /carbon ( x = 0.3) catalyst showed the highest ORR activity among the prepared catalysts. The La 0.6 Sr 0.4 Mn 0.7 Co 0.3 O 3 /carbon was tested as the cathode of an alkaline membrane-type direct hydrazine fuel cell (DHFC), and a maximum power density of 133 mW cm −2 , which exceeded that for the MEA using Pt/C (73.4 mW cm −2 ), was obtained at 50 °C. In addition, the open circuit voltage (OCV) for the DHFC (0.846 V) was greater than that of a commercial Pt/C cathode (0.788 V). Thus, the perovskite-type La 0.6 Sr 0.4 Mn 0.7 Co 0.3 O 3 catalyst is expected to be a good candidate for use as a catalytic material for a DHFC cathode as an alternative to Pt.