Developing efficient, low-cost and resource-abundant cathode catalysts plays a meaningful role for the practical application of some novel electrochemical power devices like zinc-air battery. Herein, poly-dopamine@SiO2 precursor adsorbed with graphene oxide (GO) was subjected to pyrolysis to obtain reduced GO (rG) modified ultra-thin nitrogen-doped hollow carbon sphere (NHCS) composites (2.5rG@NHCS, 5rG@NHCS and 10rG@NHCS) with different GO loadings. Among them, 5rG@NHCS performs the most efficient electroactivity for ORR in both alkaline and neutral conditions. The ORR half-wave potential are around −0.17 V for the 5rG@NHCS in 0.1 mol·l−1 KOH solution, while they are around 0.17 V for the 5rG@NHCS in a quasi-neutral solution of 4 mol·l−1 NH4Cl and 1 mol·l−1 KCl, respectively. In addition, home-made zinc-air battery with the prepared 5rG@NHCS as air electrode (cathode) catalyst performs excellent discharge capability and stability consistent with ORR results. Our work is expected to synthesize a novel metal-free catalyst with outstanding activity in both alkaline and neutral electrolytes by a versatile synthesis strategy.

Herein, N-doped carbon nanosheets/nanotubes composite loaded Fe-Co nanoparticles were prepared via a facile pyrolysis of the solid mixture composed of dicyandiamide, sucrose, cobalt nitrate, iron nitrate, iron phthalocyanine (FePc) and cobalt phthalocyanine (CoPc). The samples were characterized by SEM, TEM, XRD, XPS and BET techniques. The electroactivity of the prepared catalysts towards oxygen reduction reaction (ORR) was tested in a full pH range including acidic, neutral and alkaline media. In 0.1mol L-1 KOH solution, the ORR onset potential and half-wave potential of the FeCo-FePc/NTu-CNsh are 1.03 and 0.91 V, which are very close to the performance of commercial Pt/C catalyst (40%). In neutral solution (1 M KCl+4 M NH4Cl), FeCo-FePc/NTu-CNsh presents an ORR onset potential of 0.93 V and half-wave potential of 0.82 V, which are superior to Pt/C with onset potential of 0.92 V and half-wave potential of 0.81 V. The home-made Zn-air battery with the prepared samples as the cathodic catalysts reveal excellent performance, and the FeCo-FePc/NTu-CNsh Zn-air battery presents a maximum power density of 281.8 mW·cm-2 as well as the high stability at different discharging current densities