Fabrication of porous Co₃O₄ with different nanostructures by solid-state thermolysis of metal–organic framework for supercapacitors

Porous Co₃O₄ with different structures have been synthesized by annealing cobalt-based metal–organic framework (Co-MOF) parallelepiped microcrystals. The transformation process of nanostructures at different temperatures has been investigated, which involves the depletion of Co-MOF core, formation, and crystal growth of cobalt oxide shell. Porous hollow parallelepipeds and microsheets can be obtained at 400 and 500 °C, respectively. When evaluated as electrode materials for supercapacitors, Co₃O₄ hollow parallelepipeds exhibit better electrochemical performances compared to Co₃O₄ microsheets, which can be attributed to the unique 3D hierarchical hollow structure and small particle size.