A Binderless rGO/Fe₂O₃/PIn Ternary Nanocomposite Electrode for Supercapacitor Applications

The establishment of charge storage materials is highly needed for effective energy supply and to meet the current energy demand. Electrical energy storage technology is promising in this context and is expected to play a key role in the widespread adoption of intermittent energy sources, smart power grids, and electric vehicles. Supercapacitors with high specific capacitance, high power density, good stability, and fast charging/slow discharging features are highly desirable in an electrical energy storage device. The present work demonstrated the synthesis, characterization, and employment of a binderless polyindole-based ternary nanocomposite electrode (i.e., rGO/Fe 2 O 3 /PIn) for supercapacitor applications. The performance of rGO/Fe 2 O 3 /PIn was compared with those of Fe 2 O 3 /PIn and polyindole (PIn). Pure and modified versions of PIn were characterized for phase recognition, surface functionalities, morphology, and particle size investigations. Cyclic voltammetry and galvanostatic charge–discharge measurements suggested the capacitive nature of rGO/Fe 2 O 3 /PIn. Capacitance followed the order rGO/Fe 2 O 3 /PIn > Fe 2 O 3 /PIn > pure PIn. The highest specific capacitance of 718 F/g was recorded for rGO/Fe 2 O 3 /PIn, while it was 580 and 176 F/g, respectively, for Fe 2 O 3 /PIn and pure PIn, at a current density of 2 A/g. The rGO/Fe 2 O 3 /PIn showed improved power and energy densities. The cyclic test suggested 90.2% stability of rGO/Fe 2 O 3 /PIn after 5000 cycles. The charging–discharging mechanism of rGO/Fe 2 O 3 /PIn was proposed by using the σ-dimer model. Thus, the presently synthesized rGO/Fe 2 O 3 /PIn ternary nanocomposite could be a promising electrode material for supercapacitor applications.