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[Display omitted] • NiMn 2 O 4 -based Ni-Mn bimetallic oxides were fabricated. • The Ni-Mn bimetallic oxides access excellent ORR catalytic performance. • The Ni-Mn bimetallic oxides exhibit good discharge performance in Al-air battery. • Ni-Mn-600 has nanorod morphology and high ratio of (Mn3++Mn4+)/Mn2+ and Ni3+/Ni2+. To date, research on air battery catalysts has been mainly focused on finding materials with a high oxygen reduction reaction (ORR) catalytic activity. However, the high cost of platinum catalysts restricts their commercialization. Herein, we report a simple hydrothermal-calcination method to fabricate low-cost NiMn 2 O 4 -based Ni-Mn bimetallic oxides. The Ni-Mn-600 sample showed a high onset potential (1.01 V vs. RHE), which was more positive than that for 20 wt% Pt/C (0.97 V vs. RHE), and its half-wave potential (0.78 V vs. RHE) was comparable to that for 20 wt% Pt/C (0.84 V vs. RHE). Moreover, Ni-Mn-600 as an Al-air battery air–cathode catalyst exhibited a high discharge plateau of 1.42 V and peak power density of 100.45 mW cm−2, which outperformed those for 20 wt% Pt/C (1.34 V and 76.10 mW cm−2). The high ORR electrocatalytic activity of Ni-Mn-600 may be attributed to the nanorod morphology and high ratio of (Mn3++Mn4+)/Mn2+ and Ni3+/Ni2+. This work demonstrated that NiMn 2 O 4 -based Ni-Mn bimetallic oxides as cathode catalysts have good research prospects in aluminum-air batteries and other energy applications. [ABSTRACT FROM AUTHOR]

• ZIF-67 nanospheres were concatenated by electrospinning. • CoP was confined to N,P-doped carbon by synchronous carbonization/phosphatization. • CoP-decorated N,P-doped carbon shows an excellent oxygen reduction performance. • CoP-decorated N,P-doped carbon endows Al-air batteries with outstanding properties. Transition metal phosphides (TMPs) have attracted increasing attention as robust and efficient catalyst materials owing to their unique electronic properties and stabilities. Here, CoP-decorated N,P-doped necklace-like carbon (CoP@N,P-CNFs) was fabricated by thermal treatment of electrospun ZIF-67 spheres. The resulting CoP exhibits not only fine nanostructures but also synergistic effects with N,P-doped carbon. Polyacrylonitrile-derived nanofibers also promote the conductivity of the complex. As a consequence, CoP@N,P-CNFs exhibited excellent electrocatalytic oxygen reduction activities and Al-air battery performance. It is believed that nanofibers supporting metal-organic framework-derived heteroatom-doped carbon-encapsulated TMPs can be extended to broad applications in energy storage and conversions. [ABSTRACT FROM AUTHOR]