Self-Template Synthesis of Hybrid Porous Co₃ O₄ -CeO₂ Hollow Polyhedrons for High-Performance Supercapacitors

In this work, hybrid porous Co₃ O₄ -CeO₂ hollow polyhedrons have been successfully obtained via a simple cation-exchange route followed by heat treatment. In the synthesis process, ZIF-67 polyhedron frameworks are firstly prepared, which not only serve as a host for the exchanged Ce3⁺ ions but also act as the template for the synthesis of hybrid porous Co₃ O₄ -CeO₂ hollow polyhedrons. When utilized as electrode materials for supercapacitors, the hybrid porous Co₃ O₄ -CeO₂ hollow polyhedrons delivered a large specific capacitance of 1288.3 F g^-1 at 2.5 A g^-1 and a remarkable long lifespan cycling stability (<3.3 % loss after 6000 cycles). Furthermore, an asymmetric supercapacitor (ASC) device based on hybrid porous Co₃ O₄ -CeO₂ hollow polyhedrons was assembled. The ASC device possesses an energy density of 54.9 W h kg^-1 , which can be retained to 44.2 W h kg^-1 even at a power density of 5100 W kg^-1 , indicating its promising application in electrochemical energy storage. More importantly, we believe that the present route is a simple and versatile strategy for the preparation of other hybrid metal oxides with desired structures, chemical compositions and applications.