Hierarchical Co3O4 nanoflowers assembled from nanosheets: facile synthesis and their application in supercapacitors

In this paper, three-dimensional hierarchical Co3O4 nanoflowers have been synthesized through a redox precipitation approach followed by calcination in air. The as-synthesized hierarchical Co3O4 nanoflowers are 250 nm in size, and composed of numerous self-assembled porous ultrathin nanosheets with a thickness of 10 nm. According to the experimental results, a possible formation mechanism for hierarchical Co3O4 nanoflowers is proposed. When evaluated as an electrode material for supercapacitors, hierarchical Co3O4 nanoflowers exhibit a high specific capacitance of 198 F g(-1) at a current density of 1 A g(-1) and cycling stability (94.6 % capacity retention after 1500 cycles) in 2 M KOH electrolyte. This remarkable electrochemical performance can be ascribed to their unique structural characteristics such as open flower-like architectures and ultrathin porous nanosheets.