High-performance supercapacitors materials prepared via in situ growth of NiAl-layered double hydroxide nanoflakes on well-activated graphene nanosheets

High-performance supercapacitors materials (a-GNS/NiAl-LDH) was fabricated via in situ growth of NiAl-layered double hydroxide (NiAl-LDH) nanoflakes on well-activated graphene nanosheets (a-GNS). Graphene oxide was exfoliated and reduced using the microwave irradiation, alkali corrosion and thermal annealing in sequence. The resulting a-GNS is of large BET surface area of up to 3026 m(2) g(-1) and excellent conductivity. The as-prepared a-GNS/NiAl-LDH was characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction and infrared spectrum. The results indicated NiAl-LDH nanoflakes are well dispersed on he wrinkled graphene nanosheets. Further, the apparent electron transfer rate constant (k(s)) and electrochemical performance of a-GNS/NiAl-LDH as electrode material for supercapactiors were also investigated. The k(s) value was found to be 0.0885 cm s(-1), which is more than 2.5-fold that of pure NiAl-LDH. The a-GNS/NiAl-LDH provides a maximum specific capacitance of 1730.2 F g(-1) at current density of 0.1 A g(-1). The specific capacitance can remain 790 A g(-1) when the current density increase to 10 A g(-1), which is more than 6- and 3-fold that of pure NiAl-LDH (116.3 F g(-1)) and common GNS/NiAL-LDH (260.6 F g(-1)) made from the graphene produced by the chemical reduction of graphene oxide, respectively. The capacitance can keep at least 99.2% at current density of 5 A g(-1) after 500 cycles. These demonstrated that the use of a-GNS obviously improve the specific capacitance, high-current capacitive behavior and cycle stability. (C) 2012 Published by Elsevier Ltd.