Amorphous Co Mn binary oxides loaded on porous carbon nanosheet as bifunctional electrocatalysts for rechargeable zinc-air battery

Rechargeable zinc-air battery (RZAB) is very promising for large-scale energy storage whereas is impeded by the sluggish oxygen reduction/evolution reactions (ORR/OER). Developing high-performance yet cost-effective ORR/OER bifunctional catalysts is critical to accelerating its market penetration. Here, amorphous CoMn binary oxides loaded on porous carbon nanosheets are prepared by a facile photochemical metal- organic deposition method. The evolution of composition, microstructure, ORR/OER performance with the calcination temperature is systematically investigated. The amorphous CoMn2Ox supported on carbon nanosheets shows higher ORR/OER bifunctional electrochemical performance in terms of activity and stability. The resultant RZAB with the amorphous CoMn2Ox on carbon nanosheets as air electrode delivers a peak power density of 89.6 mW cm−2 and maintains stable operation for ∼500 cycles at 10 mA cm−2. The ORR/OER bifunctional performance is closely associated with the microstructure, oxidation states of Co/Mn species and their corresponding proportions. Although there is great room to performance enhancement, this work sheds light on the development of high-performance and cheap ORR/OER bifunctional catalysts for rechargeable metal-air batteries by engineering the crystallinity of the metal oxides.