Hierarchically porous Co3O4 film prepared by hydrothermal synthesis method based on colloidal crystal template for supercapacitor application

Hierarchically porous Co3O4 film is prepared via a hydrothermal synthesis method based on a self-assembled monolayer polystyrene (PS) spheres template. The as-prepared Co3O4 film shows a two-layer structure: substructure is composed of Co3O4 monolayer hollow-sphere array and the superstructure consists of porous net-like Co3O4 nanoflakes possessing continuous mesopores ranging from 2 to 5 nm. The pseudocapacitive behavior of the hierarchically porous Co3O4 film is investigated by cyclic voltammograms (CV) and galvanostatic charge-discharge tests in 2 M KOH. As cathode material for supercapacitors, the hierarchically porous Co3O4 film exhibits noticeable pseudocapacitive properties with a capacitance of 454 F g(-1) at 2 A g(-1) as well as quite good cycling stability and high capacitance retention. Compared to the film prepared without template, the hierarchically porous film exhibits weaker polarization, higher capacitances and better cycling performance. The enhancement of pseudocapacitive properties are due to the hierarchically porous architecture, which provides fast ion/electron transfer and alleviates the structure degradation caused by volume expansion during the cycling process. (C) 2012 Elsevier Ltd. All rights reserved.