PBA-derived FeCo alloy with core-shell structure embedded in 2D N-doped ultrathin carbon sheets as a bifunctional catalyst for rechargeable Zn-air batteries

To overcome slow kinetics of oxygen reduction/evolution reactions (ORR/OER), the development of bifunctional electrocatalysts remains a huge challenge. FeCo alloy as an active-species usually suffers from its poor catalytic stability by easy corrosion. Here, we synthesize a core (FeCo)-shell (carbon) alloy anchored on nitrogen-doped porous carbon-nanosheets (FeCo/NUCSs) via a self-growth strategy. FeCo/NUCSs (140 m2 g-1) exhibits promising half-wave potential (E1/2 =0.89 V) and methanol tolerance for ORR. Prussian blue analog-derived carbon shell protects binary active-sites (Fe-Nx/Co-Nx) on FeCo core to stabilize ORR activity. FeCo/NUCSs also displays a higher OER activity (overpotential of 300 mV) than RuO2, due to generation of highly-active FeOOH/CoOOH species on FeCo alloys as indicated by in situ X-ray diffraction. Assembled Zn-air battery (ZAB) exhibits promising open-circuit voltage of 1.51 V, specific capacity of 791.86 mA h g-1, and durability (102 h). This novel bimetallic alloy-based catalyst provides an interesting option for design of durable oxygen-electrocatalysts for ZAB.

Automated summary

By synthesizing a core-shell FeCo alloy/carbon nanosheets composite, we have successfully enhanced the catalytic activity and stability of oxygen reduction reactions. The composite material also exhibits excellent oxygen evolution reaction activity and potential application in zinc-air batteries.