Bimetallic\nMetal–Organic-Framework/Reduced\nGraphene Oxide Composites as Bifunctional Electrocatalysts for Rechargeable\nZn–Air Batteries

Abstract

The most challenging issue in the development\nof metal–air batteries is the insufficient catalytic activity\nof the cathode toward oxygen evolution and reduction reactions (OER/ORR).\nMetal–organic frameworks (MOFs) and MOF-based electrocatalysts\nhave drawn considerable attention for the replacement of noble-metal\nelectrocatalysts. Here, the rational design and synthesis of bimetallic\nCoNi-MOF nanosheets/reduced graphene oxide (rGO) hybrid electrocatalysts\nis reported. The CoNi-MOF nanosheets were in situ grown onto rGO assisted\nby the surfactant modulation. The newly developed CoNi-MOF/rGO hybrids,\nconsisting of homogeneously distributed nanosheets encapsulated by\nrGO, display excellent electrocatalytic activities toward OER and\nORR. The much improved bifunctional catalytic performance is ascribed\nto the synergy among the CoNi-MOF nanosheets and rGO, the abundant\nexposed active sites, and the enhanced electron conductivity. Moreover,\nthe rechargeable Zn–air batteries with CoNi-MOF/rGO-based air\nelectrodes display high energy density and cycling stability, demonstrating\nthe great potential as advanced bifunctional electrocatalysis in electronic\ndevices.