▎ 摘　　要

Exploring non-noble oxygen electrode catalysts for efficient and stable oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of great importance for high-performance rechargeable zinc-air batteries. In this work, we reported for the first time that 2-methylimidazole (2-MIM) can effectively regulate the loading of transition metals nickel (Ni) and iron (Fe) on nitrogen-doped graphene hollow spheres (NGHS) entangled with N-doped carbon nanotubes (NCNTs). The introduction of 2-MIM not only effectively controls the size of loaded metal nanoparticles (NPs), but also plays a significant role in the formation of the metal alloy. In addition, the introduction of Ni is the key factor for the self-growth of NCNTs, and the introduction of Fe serves a key role in promoting the formation of metal nitrides and improving the bifunctional performance of the electrode materials. The NiFe3@NGHS-NCNTs obtained after optimization of the preparation parameters exhibit excellent ORR/OER bifunctional electroactivity and long-term durability, which has obvious advantages over commercial 20% Pt/C + RuO2 catalysts. Density functional theory (DFT) calculation demonstrated that the NiFe3 alloy is strongly coupled with N-doped carbon (NC), endowing the C active site with moderate positive charge and valence state, thus improving the ORR and OER performance of the NiFe3@NGHS-NCNTs. More importantly, a rechargeable liquid electrolyte Zn-air battery (ZAB) with NiFe3@NGHS-NCNTs as the air cathode delivers a comparatively small charge-discharge voltage gap of 0.737 V at 10 mA cm(-2) and displays maximum power density of 126.54 mW cm(-2), which is higher than that of the commercial 20% Pt/C + RuO2 catalyst (102.63 mW cm(-2)). The fabricated flexible all-solid-state (ASS) rechargeable ZAB with NiFe3@NGHS-NCNTs exhibits a higher open-circuit voltage (OCV) (1.44 V) and peak power density (102.82 mW cm(-2)) than ASS-ZABs based on 20% Pt/C + RuO2 (1.42 V, 35.35 mW cm(-2)).