Eco-Friendly Enrichment of Tainted Fe₃O₄ Nanoparticles and Fe₃O₄-rGO Nanocomposites for Superior Supercapattery Performance

The preparation of unique nanocomposites (NCs) by integrating Fe3O4 nanoparticles (NPs) on reduced graphene oxide (rGO) toward photocatalysis and supercapattery applications is systematically investigated. The X-ray photoelectron spectroscopy (XPS) examination of the synergistic effect between the Fe3O4-rGO (6%) composite provided evidence of the existence of Fe–O–C bonds. Consequently, the catalytic activity of Fe3O4 NPs and all Fe3O4-rGO NCs tested against methylene blue (MB) dye, and the photocatalytic performance evaluation showed that the Fe3O4-rGO (6%) composite demonstrated superior degrading efficiency (98.7% at 140 min) than that of other materials. Subsequently, the tainted catalyst materials were repurposed as cathode materials for supercapattery application. Moreover, the tainted Fe3O4-rGO (6%) composite demonstrated an exceptional specific capacity (Cs) value of 1308.6 C·g–1, which exhibits a remarkable rate capability compared to that of other materials. Leveraging this superiority, an asymmetric supercapattery (ASC) device is meticulously engineered, achieving Cs values of 1088 C·g–1. This achievement owes itself to the device’s remarkable energy density (E) of 81.75 Wh·kg–1 and an impressive power density (P) at 313.51 W·kg–1. In addition, the supercapacitor device showed an outstanding 97% capacity retention during 2000 cycles of charging and discharging. The device can light up an LED bulb for 135 s. Moreover, tainted catalyst materials are promising candidates for energy storage applications.