Fabrication of Hierarchical Porous Metal-Organic Framework Electrode for Aqueous Asymmetric Supercapacitor

As promising electrode materials in supercapacitors, metal-organic frameworks (MOFs) have attracted significant attention. However, the poor electrical conductivity and the almost exclusively microporous structure largely limited the possibility for MOFs to fabricate high-performance electrodes of supercapacitors. To overcome these obstacles, hierarchical porous Zr-MOFs (HP-UiO-66) has been successfully fabricated using bimetallic Zn/Zr MOFs as a precursor, subsequently wiping off Zr-MOFs. When used as electrode materials for supercapacitors, under a current density of 0.2 A g^-1, the specific capacitance of the prepared HP-UiO-66 is 849 F g^-1, which is 8.36 times higher than the 101.5 F g^-1 of bare UiO-66. The clearly enhanced electrochemical performance of HP-UiO-66 was benefited from the advantages of the hierarchical porous structure, the higher specific surface area and pore volume, as well as the sufficient surface defects. Furthermore, an aqueous asymmetric supercapacitor based on the HP-UiO-66 and porous carbon could show an energy density of 32 W h kg^-1 at a power density of 240 W kg^-1. This strategy may offer a versatile idea of tailoring new type of MOFs and opens the possibility of MOFs using in the future high-energy storage device.