Boosting oxygen reaction activity by coupling sulfides for high-performance rechargeable metal–air battery†
Sluggish oxygen electrochemistry including both oxygen evolution reactions (OER) and oxygen reduction reactions (ORR) greatly restricts the performance of rechargeable metal–air battery. Herein, we couple NiFe sulfide (NiFeS2) with S-doped graphene oxide (S-GO) via a simultaneous sulfurization strategy to significantly improve the OER and ORR activities. The NiFeS2/S-GO on glassy carbon yields an OER current density of 10 mA cm−2 at 1.47 V and an ORR half-wave potential at 0.74 V (vs. RHE), giving an overvoltage difference as low as 0.73 V. When assembled in a rechargeable Zn–air battery, the battery with NiFeS2/S-GO air electrode exhibits a steady charging potential (1.98 V) with very little decay in discharging potential (from 1.20 to 1.17 V) for 180 charging–discharging cycles at 10 mA cm−2. Our study provides new insights for the design of efficient bifunctional oxygen electrocatalysts for high-performance energy conversion and storage devices.