Improved electrocatalytic activity of hexagonal prisms Fe3O4 derived from metal-organic framework by covering dendritic-shaped carbon layer in Li–O2 battery

Abstract

The lithium-oxygen batteries (LOBs) have gained extensive interest in the past decade, but are plagued by slow reaction kinetics and induced large-voltage hysteresis. Therefore, developing extremely capable catalysts to enhance catalytic behavior and mitigate oxidation-reduction overpotential of LOBs is of huge challenge and significance. Attributable to their economically friendly and great activity, transition metal oxides (TMO) have incurred lots of attention as alternative electrocatalysts to replace the currently used noble metal-based catalysts. In this work, we fabricate a highly efficient TMO (the MIL-88A heated at 500 °C under protective flow, M8-Fe 3 O 4 @NC-500) electrocatalyst as advanced cathodes, which attributed to its unique structure, numerous dendritic-shaped carbon layer was anchored inplane into the micrometer-long spindle-shaped prisms with evenly distribution and contains abundant Fe–N/Graphitic N active sites. Therefore, the LOBs (based on M8-Fe 3 O 4 @NC-500/AB cathode) deliver superior electrochemical performance with large specific capacities of 14866.1 mAh g −1 , low overpotentials (1.31 V), and steady cycling stability (553 cycles, limited 500 mAh g −1 , under 0.05 mA cm −2 ). Our work provides a novel vision to rationally design and synthesize a powerful TMO electrocatalyst (with the 2D carbon nanosheet coating) for the LOBs cathode.