Fabrication of free-standing graphene/polyaniline nanofibers composite paper via electrostatic adsorption for electrochemical supercapacitors

Flexible graphene sheet (GS)/polyaniline (PANi) nanofibers composite paper was prepared via a facile and fast two-step route composed of electrostatic adsorption between negatively-charged poly(sodium 4-styrenesulfonate) (PSS) mediated GS (coded as PSS-GS) and positively-charged PANi nanofibers and the follow-up vacuum filtration of the as-prepared PSS-GS/PANi nanofibers suspension. By observations of field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM), it is clearly seen that representative and highly ordered layered PSS-GS/PANi composite papers have been achieved and PANi nanofibers are coated by PSS-GS. In addition, the synthesized PSS-GS/PANi composite papers are also characterized by Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy, and the results further confirm the successful synthesis of PSS-GS/PANi composites and the existence of strong interaction between PSS-GS and PANi nanofibers. The most interesting thing is the effective synergy can remarkably improve electrochemical properties of GS by introducing PANi nanofibers, which can ascribe to high surface area of GS and good combination between PSS-GS and PANi nanofibers. The highest specific capacitance of the composites reaches 301 F/g. Thermogravimetry analysis (TGA) indicates that the thermal stability of the PSS-GS/PANi composites is obviously improved compared to the pure PSS-GS and PANi.