Fe-intercalated few layers reduced graphene oxide: A unique material for supercapacitor applications

Abstract

Although intensive research has been carried out on composite materials containing transition metal (TM) oxides and graphene for supercapacitor application, the field remains totally unexplored to intercalate TM atoms in few layer reduced graphene oxide (rGO) to design high performance supercapacitors. The major advantages are the enhancement in porosity and formation of trap states at the Fe sites for better charge storage capacity. Therefore, in the present work, Fe-intercalated few layer rGO samples are synthesized to enhance the interlayer separation from 0.34 to ∼1 nm. The enhancement of interlayer separation is characterized by x-ray diffraction, which shows a single peak at a 2θ value of 8.7°, indicating the layered type material with an interlayer separation of 1 nm. Large enhancement in specific capacitance to about 896 F/g and a high energy density of 31 W h/kg is observed in this highly porous material. All these results of enhancement in specific capacitance and energy density are explained on the basis of trap states created at the Fe sites and large enhancement in porosity due to Fe intercalation. Cyclic stability to about 85% after 8000 cycles is also verified. Quantitative evaluation of trap states and modification of charge transport are observed. Due to trap centers, a high value of dielectric permittivity is achieved.