Controlled synthesis of a cobalt-organic framework: hierarchical micro/nanospheres for high-performance supercapacitors

Abstract

The integration of metal–organic frameworks (MOFs) and hierarchical micro/nanostructures has attracted great interest because of their potential in energy-related applications. Herein, we present a strategy to synthesize Co-MOF-based hierarchical micro/nanospheres (Co-MOF/M1, Co-MOF/M2, and Co-MOF/M3) with ultrathin nanosheet subunits by adjusting the content of the cobalt chloride precursor and the pyridine-3,5-dicarboxylic acid ligand. These micro/nanospheres feature a 3D architecture with exposed active sites and abundant channels for fast electron and electrolyte transport, which is suitable for supercapacitor applications. The optimized sample Co-MOF/M2 exhibits a high specific capacitance (430 F g⁻¹ at 0.5 A g⁻¹) and excellent rate performance (92.4% capacitance retention at a current density of 5 A g⁻¹).