MOF-Derived Hollow and Porous Co₃O₄ Nanocages for Superior Hybrid Supercapacitor Electrodes

The development of hollow and porous materials is essential for effective energy storage and conversion owing to their facile transport of electrons and ions. Herein, through a facile low-temperature thermal decomposition reaction of ZIF-67 crystals, hollow Co3O4 nanocages composed of numerous nanoparticles with a porous structure are prepared. These hollow and porous Co3O4 nanocages (Co3O4 HPCs) possess a pore size distribution between 20 and 60 nm and a large Brunauer-Emmett-Teller surface area of 211.79 m(2) g(-1). Benefitting from the large surface area, a maximum specific capacitance of 140.0 F g(-1) can be calculated. Furthermore, the assembled Co3O4 HPCs//activated carbon hybrid supercapacitor can deliver an energy density of 19.8 W h kg(-1) and 97.3% capacitance retention during 5000 cycles. As a result of good electrochemical performance of these Co3O4 HPCs, they can be a promising electrode for supercapacitors.