Effects of graphene reduction degree on capacitive performances of graphene/PANI composites

Abstract

Reduced graphene oxide (RGO) was compounded with polyaniline (PANI) to prepare supercapacitor electrode materials. For the preparation, graphene oxide (GO) was reduced with glucose and ammonia, and then PANI was in situ deposited onto the RGO nano-sheets by polymerizing aniline with ammonium persulfate (APS) as oxidizing agent. The obtained composites were characterized with scanning electron microscope, Fourier transform infrared spectroscopy, Raman spectroscopy, UV–vis absorption spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy (EIS). It was found that with increasing reduction time, the oxygen content on the surface of GO was decreased, leading to increased ID/IG ratio in the Raman spectra of GO and increased conductivity of GO. Consequently, the capacitance properties of RGO/PANI composites could be significantly improved by the reduction of GO. It was also observed that the initial concentrations of aniline being used for the polymerization could influence the rate performance of the composite. Under the optimal preparation conditions (the reduction time of graphene 60min, the initial concentration of aniline 0.025molL−1, and the molar ratio of aniline to APS 1:1), the obtained composites exhibited a specific capacitance as high as 1045Fg−1, along with a retention of 97% after 1000 cycles.