▎ 摘　　要

Graphene aerogel-supported manganese ferrite (MnxFe3-xO4/GAs) and reduced-graphene oxide/manganese ferrite composite (MnFe2O4/rGO) were synthesized and studied as cathode catalysts for oxygen reduction reactions in urea/O-2 fuel cells. MnFe2O4/GAs exhibited a 3D framework with a continuous macroporous structure. Among the investigated Fe/ Mn ratios, the more positive oxygen reduction onset potential was observed with Fe/Mn=2/1. The half-wave potential of MnFe2O4/GAs was considerably more positive than that of MnFe2O4/rGO and comparable with that of Pt/C, while the stability of MnFe2O4/GAs significantly higher than that of Pt/C. The best urea/O-2 fuel cell performance was also observed with the MnFe2O4/GAs. The MnFe2O4/GAs exhibited an OCV of 0.713 V and a maximum power density of 1.7 mWcm(-2) at 60 degrees C. Thus, this work shows that 3D structured graphene aerogelsupported MnFe2O4 catalysts can be used as an efficient cathode material for alkaline fuel cells.