Fabrication of porous nickel oxide film with open macropores by electrophoresis and electrodeposition for electrochemical capacitors

The electrophoretic deposition of polystyrene sphere monolayer as a template for anodic electrodeposition of interconnected nickel oxide nanoflakes is explored. Result indicates that a nickel oxide film with nanoflakes and open macropores has superior capacitive behavior. A nickel oxide film with interconnected nanoflakes is of great importance for electrochemical capacitors due to the high-specific surface area, fast redox reactions, and shortened diffusion path in solid phase. The open macropores may facilitate the electrolyte penetration and ion migration, therefore increasing the utilization of nickel oxide due to the increased surface area for electrochemical reactions. The specific capacitance of a nickel oxide film with open macropores at a scan rate of 10 mV s−1 reaches as high as 351 F g−1, which is 2.5 times higher than that of the bare nickel oxide film (140 F g−1).