Hierarchically porous NiO film grown by chemical bath deposition via a colloidal crystal template as an electrochemical pseudocapacitor material

Hierarchically porous NiO film has been successfully prepared by chemical bath deposition through monolayer polystyrene sphere template. The film possesses an architecture with a substructure of NiO monolayer hollow-sphere array and a superstructure of porous net-like NiO nanoflakes. The pseudocapacitive behavior of the NiO film is investigated by cyclic voltammograms (CV) and galvanostatic charge-discharge tests in 1 M KOH. The hierarchically porous NiO film exhibits weaker polarization, better cycling performance and higher specific capacitance in comparison with the dense NiO film. The specific capacitance of the porous NiO film is 309 F g(-1) at 1 A g(-1) and 221 F g(-1) at 40 A g(-1), respectively, much higher than that of the dense NiO film (121 F g(-1) at 1 A g(-1) and 99 F g(-1) at 40 A g(-1)). The hierarchically porous architecture is responsible for the enhancement of electrochemical properties.