A nickel hydroxide-coated 3D porous graphene hollow sphere framework as a high performance electrode material for supercapacitors.

A three-dimensional (3D) porous graphene hollow sphere (PGHS) framework has been fabricated via a hard template method and used to anchor α-Ni(OH)2 nanoparticles with the size of about 4 nm through electrochemical deposition. It is found that a 3D PGHS framework can improve the capacitive performance of Ni(OH)2 effectively. In hybrid materials, α-Ni(OH)2 achieves the high specific capacitance of 2815 F g(-1) at a scan rate of 5 mV s(-1) and 1950 F g(-1) even at 200 mV s(-1) with a capacitance retention of about 70%, indicating that the α-Ni(OH)2-coated 3D PGHS framework exhibits high rate capability. The excellent performance of such hybrid material is believed to be due to the smaller size of Ni(OH)2 nanoparticles and the PGHS framework with large specific surface area promoting efficient electron transport and facilitating the electrolyte ions migration. These impressive results suggest that the composite is a promising electrode material for an efficient supercapacitor.