Novel π-conjugated iron oxide/reduced graphene oxide nanocomposites for high performance electrochemical supercapacitors

Abstract

A novel nanocomposite consisting of π-conjugated 2-aminoterephthalic acid (ATA) coated iron oxide (Fe₃O₄) nanoparticles and reduced graphene oxide (RGO) has been synthesized using a facile combination of wet-chemistry and low-power sonication. The ATA–Fe₃O₄/RGO nanocomposites exhibited a high specific capacitance of the order of 576 F g⁻¹; significantly higher than that of pristine Fe₃O₄ (132 F g⁻¹) and RGO (60 F g⁻¹) counterparts, indicative of a synergistic effect between the ATA–Fe₃O₄ and RGO components. Furthermore, the maximum energy storage density was calculated to be 75 W h kg⁻¹ (at a current density of 6 A g⁻¹). The charging–discharging analysis showed promising long-term stability with nearly 86% retention of the capacitance after 5000 cycles. The superior capacitive behaviour of these ATA–Fe₃O₄/RGO nanocomposites is attributed to the synergistic effect of the π-conjugated ATA coating on Fe₃O₄ which enhances the pseudo-capacitive charge transfer process of Fe₃O₄ and works in conjunction with the surface functional groups (such as carboxylic, amino and amide) present on the RGO surface, providing enhanced double layer capacitance. Thus, the current system exploits the advantages of both the double layer capacitors and pseudocapacitors in a hybrid structure.