Synthesis of three-dimensional self-standing graphene/Ni(OH)₂ composites for high-performance supercapacitors

Using surface active agents, three-dimensional (3D) self-standing graphene/Ni(OH)₂ composites with different morphologies, such as nanoflowers, nanoslices and nanoparticles, are directly synthesized by a facile in situ electrodeposition method. SEM and Raman spectroscopy are used to investigate the morphologies and structures. Detailed electrochemical characterizations reveal that the 3D graphene/Ni(OH)₂ nanoflower exhibits high specific capacitance (718.2 F g^-1 at 6.7A g ^-1 in 6.0 M KOH aqueous solution) and good cycling performance (84.2% capacitance retention after 500 cycles) compared with those of other Ni(OH)₂ morphologies. Nyquist plot investigation shows that 3D graphene/Ni(OH)₂ nanoflowers present a low equivalent series resistance. These results indicate that the composite may be a promising candidate for high-performance supercapacitors.