Reduced graphene oxide/carbon nanotube/α-Ni(OH)2 (RGO/CNT/α-Ni(OH)2) composites are successfully synthesized by a one-pot hydrothermal route. The structural characterization of the composites by EDX, XRD, FT-IR, XPS, Raman, FESEM and TEM indicate that α-Ni(OH)2 nanoparticles with the size around 5 nm are randomly decorated onto three-dimensional (3D) hierarchical structure RGO/CNT. The electrochemical performances of the composites are evaluated by cyclic voltammogram, galvanostatic charge-discharge and electrochemical impedance spectroscopy. Interestingly, it is found that the electrochemical capacitance of the composites depends on the amount of CNTs to a large extent and RGO/CNT/α-Ni(OH)2 composite (GC2Ni2) with optimized ratio exhibits the high specific capacitance of 1320 F g−1 at 6 A g−1. In addition, the cycling measurements show that GC2Ni2 maintains a specific capacitance of 1008 F g−1 at 15 A g−1 after 1000 cycles corresponding to a reduction of capacitance of about 7.8%. The enhancement in specific capacitance and cycling stability is believed to be due to the 3D RGO/CNT conductive network which promotes not only efficient charge transport and facilitates the electrolyte diffusion, but also prevents effectively the volume expansion/contraction and aggregation of electroactive materials during charge-discharge process. These impressive results suggest that the hybrid composite is a promising supercapacitor electrode material.
http://www.sciencedirect.com/science/article/pii/S0378775313006745
