Construction of 1D/2D hierarchical carbon structure encapsulating FeCo alloys by one-step annealing leaf-like ZnFeCo-ZIF for highly-efficient bifunctional oxygen electrocatalysis in reversible Zinc-air battery

Developing cost-effective, efficient and stable air cathodes, involving oxygen reduction/oxygen evolution reactions (ORR/OER), is the crux of the large-scale application of reversible Zinc-air batteries. Herein, 1D/2D hierarchical N doping carbon architecture encapsulating FeCo nanoalloys were successfully constructed by onestep annealing leaf-like ZnFeCo-ZIFs. Benefiting from the unique 1D/2D hierarchical porous feature with high specific surface area, sufficient accessible catalytic sites, not easy entanglements and efficient electron and mass transfer capacity, as well as the advantages of the strong electronic coupling in FeCo alloys, the as-prepared FeCo@ 1D-CNTs/2D-NC catalysts exhibited prominent bifunctional oxygen catalytical performances with a positive half-wave potential (E1/2 = 0.87 V vs. reversible hydrogen electrode (RHE)) for the oxygen reduction reaction and a low overpotential (eta 10 = 396 mV) at a current density of 10 mA cm-2 for the oxygen evolution reaction, manifesting a low reversible potential gap (Delta E = 0.756 V). The zinc-air battery equipped with FeCo@ 1D-CNTs/2D-NC as the cathode catalyst exhibited a higher peak power density (98.2 mW cm-2) and specific capacity (741 mAh gZn-1) than that assembled with the commercial Pt/C This study provides a convenient strategy to explore non-precious metal based bifunctional electrocatalysts for reversible Zinc-air battery scale applications.