Hierarchical 2D Cu-MOF@Graphene-Based Hybrids for Supercapacitor Electrodes

Recently, two-dimensional metal-organic framework (2D MOF) hybrids are attracting much attention in supercapacitors. However, their performance is limited by the insufficient utilization of active sites and poor conductivity. Notably, the full utilization of active sites highly depends on the fast transport and diffusion of ions. Here, a Cu-MOF@GO-COOH hybrid was constructed, with GO-COOH as the substrate, to promote electron transfer, and Meso-Cu-MOF@GO-COOH was further obtained by introducing mesopores inside nanosheets to optimize the transportation paths for ions. The GO-COOH substrate improves the capacitance by enhancing the surface capacitive behavior, while the mesopores improve the charge-storage capacity by enhancing the diffusive behavior. The as-obtained Meso-Cu-MOF@GO-COOH exhibits a higher capacitance of 292.5 F g^-1 compared with Cu-MOF@GO-COOH (193.7 F g^-1) and 2D Cu-MOF (141.4 F g^-1) at a current density of 1 A g^-1. Moreover, the prepared Cu-MOF@GO-COOH//AC device delivers a capacitance of 63 F g^-1 (0.5 A g^-1), an energy density of 27.7 Wh kg^-1, and a power density of 496.8 W kg^-1, showing a great potential for practical applications.