Octahedral Rigid-Flexible Core-Shell UiO-66@PPy Electrodes with Boosting Charge Transport for Supercapacitors

Poor conductivity of UiO-66 severely limited the electrochemical performances in the supercapacitors, which were alleviated and improved by combining with polypyrrole (PPy) with high conductivity and pseudocapacitive properties. Herein, a series of UiO-66@x%PPy ( x = 5 , 1 0 , 2 0 , 3 0 ) composites were prepared by solvothermal reaction followed by in-situ polymerization of pyrrole(PPy); furthermore, the influence of PPy’s loading on the structural properties was also systematically investigated. Desirably, the obtained composites maintained the “rigid-flexible” core-shell octahedral structure. Furthermore, the UiO-66@20%PPy composite exhibited the highest electrochemical performances with the specific capacitance of 204.1 F/g in a three-electrode system and 118.18 F/g in a two-electrode system at 1 A/g. Furthermore, the asymmetric two-electrode supercapacitor exhibited a high capacitance retention of 88.25% after 2000 cycles at 2 A/g. The synergistic effect between the continuous three-dimensional (3D) conductive network of PPy phase and the double-layer capacitance of porous UiO-66 framework may be responsible for the desirable results. Seemingly, an effective interfacial strategy was indeed beneficial for developing a high-performance UiO-66-based supercapacitor.