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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/O2 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/O2 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 mW cm−2 at 60 °C. Thus, this work shows that 3D structured graphene aerogel‐supported MnFe2O4 catalysts can be used as an efficient cathode material for alkaline fuel cells. [ABSTRACT FROM AUTHOR]

Abstract: Nanopowders of FeAl and Al2O3 were synthesized from Fe2O3 and Al by high energy ball milling. The sizes of FeAl and Al2O3 were 4 and 57nm, respectively. A dense nanostuctured FeAl–Al2O3 composite was consolidated by a high-frequency induction heated sintering method within two minutes from mechanically synthesized powders of FeAl and Al2O3. The grain size, sintering behavior and hardness of the sintered FeAl–Al2O3 composite were investigated. [Copyright &y& Elsevier]

Graphene aerogel-supported manganese ferrite (Mn x Fe 3-x O 4 /GAs) and reduced-graphene oxide/manganese ferrite composite (MnFe 2 O 4 /rGO) were synthesized and studied as cathode catalysts for oxygen reduction reactions in urea/O 2 fuel cells. MnFe 2 O 4 /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 MnFe 2 O 4 /GAs was considerably more positive than that of MnFe 2 O 4 /rGO and comparable with that of Pt/C, while the stability of MnFe 2 O 4 /GAs significantly higher than that of Pt/C. The best urea/O 2 fuel cell performance was also observed with the MnFe 2 O 4 /GAs. The MnFe 2 O 4 /GAs exhibited an OCV of 0.713 V and a maximum power density of 1.7 mW cm -2 at 60 °C. Thus, this work shows that 3D structured graphene aerogel-supported MnFe 2 O 4 catalysts can be used as an efficient cathode material for alkaline fuel cells., Competing Interests: The authors declare no conflict of interest.