Sol-gel synthesized BiFeO3-Graphene nanocomposite as efficient electrode for supercapacitor application

In the present work, bismuth iron oxide-graphene composite has been explored as electrode material for electrochemical supercapacitor application. Bismuth iron oxide (BFO) nanoparticles, synthesized by sol-gel process, are mixed with the graphene sheets in a solution. The electrodes are prepared by coating the resulted slurry on stainless steel (SS) substrate, by drop casting process. The morphology and structure of the BFO-graphene composite are characterized by XRD, FIB-SEM, HRTEM and Raman spectroscopy, which show that the nanoparticles with diameter 100-200 nm are randomly distributed on and around the graphene sheets. The composite electrode exhibits significantly enhanced capacitance as compared to BFO. In this structure, the electrons generated by the surface based Faradaic reactions from the BFO nanoparticles can be transported by the graphene nanosheets toward the current collector. The electrochemical characteristic of the electrodes is investigated through cyclic voltammetry and charging/discharging process. The specific capacitance of the electrode measured at 5-100 mV/s was found to be 17-4 mF/cm(2) which is comparable to the most commonly used metal oxide based electrode materials. It shows better cycling stability with 95% retention of capacitance after 2000 cycles.