A novel hierarchical graphene/polyaniline hollow microsphere as electrode material for supercapacitor applications

A hierarchical graphene/polyaniline hollow microspheres with sandwich structure (GCS@PANI@RGO) have been successfully synthesized by the in situ polymerization of PANI on the surface of graphene carbon sphere (GCS) and then the electrostatic self-assembly of graphene oxide and reduction without etching templates. The morphologies and microstructures of the microspheres were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy and nitrogen adsorption measurements. The results show that the GCS@PANI@RGO composites demonstrate desirably hierarchical hollow microspheres with sandwich structure and the strong interactions such as electrostatic interactions, hydrogen bonding and π–π interactions existed between the layers in hierarchical hollow microspheres. The electrochemical behaviors of GCS@PANI@RGO as electrode were investigated by cyclic voltammograms, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The GCS@PANI-8@RGO showed a high specific capacitance of 446.19 F g−1 at the scanning rate of 5 mV s−1 in 1 M H2SO4 solution, and exhibit an outstanding long-term cycling stability with capacitance retentions of 93.4% after 1000 charging–discharging cycles at a current density of 2 A g−1 and even 88.7% after 5000 cycles. The excellent electrochemical performance can be ascribed to the novel sandwiched hollow structure, and the synergic effect of the three components of GCS, PANI and RGO, which greatly enhance the electrical conductivity, promote the utilization of active materials and improve the structural stability. Therefore, such novel hierarchical hollow materials could be considered as quite suitable and promising electrodes for high-performance supercapacitors.