Free-Standing Working Electrodes for Supercapacitors Based on Composite Polymer Nanofibers and Functionalized with Graphene Oxide

Hybrid capacitors have the potential to combine the benefits of both electrochemical double-layer capacitors and faradaic capacitors. Supercapacitor electrodes can combine carbon-based and conductive polymers to achieve this potential and to deliver energy more than dielectric capacitors, and power densities more than Li-ion batteries. Polyindole (PIND) is a promising candidate for supercapacitors due to its unique physical and electrochemical properties. PIND was prepared chemically via oxidative polymerization. A laboratory-made electrospinning method has been successfully utilized to manufacture nanofibers from a blend of PIND and ultrahigh molecular weight polyacrylonitrile (PAN) to impart adequate chain entanglements. A tiny amount of graphene oxide (GO) was introduced to a solution of PIND/PAN before electrospinning to yield PIND/PAN/GO nanofibers to further improve the stability and conductivity of the electrodes. The chemical structure of the synthesized materials was investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR). The electrochemical behavior of the prepared nanofibers was tested via the measurements of galvanostatic charge–discharge (GCD) and cyclic voltammetry (CV). It was found that the PIND/PAN/GO nanofiber webs exhibited a specific capacitance of 4960 mF g −1 which is higher than that of PIND/PAN nanofiber webs (1810 mF g −1 ) in 1 M H 2 SO 4, at the same scanning rate in CV measurements. The results indicated that electrospinning as a cost-effective technique can be used successfully to fabricate free-standing electrodes from PIND, as well as illustrate the role of GO in enhancing the charge storage of PIND electrodes. Graphic Abstract Supercapacitor electrodes from PIND/PAN/GO nanofibers