Nickel-Nitrogen Doped MnO as Oxygen Reduction Reaction Catalyst for Aluminum Air Batteries.

Aluminum-air battery has the advantages of high energy density, low cost and environmental protection, and is considered as an ideal next-generation energy storage conversion system. However, the slow oxygen reduction reaction (ORR) in air cathode leads to its unsatisfactory performance. Here, we report an electrode made of N and Ni co-doped MnO nanotubes. In alkaline solution, Ni/N-MnO has higher oxygen reduction activity than undoped MnO, with an initial potential of 1.00 V and a half-wave potential of 0.75 V. This is because it has abundant defects, high specific surface area and sufficient Mn active sites, which promote the transfer of electrons and oxygen-containing intermediates. Density functional theory (DFT) calculations show that MnO doped with N and Ni atoms reduces the reaction overpotential and improves the ORR kinetics. The peak power density and energy density of the Ni/N-MnO air electrode increased by 34.03 mW cm and 316.41 mWh g, respectively. The results show that N and Ni co-doped MnO nanotubes are a promising air electrode, which can provide some ideas for the research of aluminum-air batteries.