Synergistic performance of Fe 3 O 4 / SnO 2 / rGO nanocomposite for supercapacitor and visible light‐responsive photocatalysis

The performance of nanomaterials in energy storage devices and catalysts is influenced by their size and surface area. In addition, because the surface accessibility to ions or reactants significantly affects the performance of the devices, the surface area and pore structure of the nanomaterials are critical design parameters. Herein, a nanocomposite containing Fe3O4, SnO2, and reduced graphene oxide (rGO) is synthesized that exhibits superior pore structure and a significantly larger surface area (217.39 m2 g−1) compared to the single-metal-oxide composites, Fe3O4/rGO (68.88 m2 g−1) and SnO2/rGO (56.80 m2 g−1). Fe3O4/SnO2/rGO is used as a supercapacitor and a dye-degrading photocatalyst, achieving a superior-specific capacitance of 967.5 F g−1 at a current density of 1 A g−1 and long cycle stability (98% capacity retention over 5000 cycles at 10 A g−1). The photocatalytic activity of Fe3O4/SnO2/rGO was evaluated under visible light and showed significant degradation (92%) of methylene blue dye. The unexpectedly high surface area of Fe3O4/SnO2/rGO is credited to the synergistic interactions of Fe3O4, SnO2, and rGO, which prevent the growth and agglomeration of nanoparticles and thereby increase the surface area and electrical conductivity. These results provide meaningful insights to further improve the synthesis of active materials and catalysts with a large surface area via hydrothermal methods. Highlights High surface area (217.39 m2/g) hydrothermally-grown Fe3O4/SnO2/rGO Nanocomposite. Fe3O4/SnO2/rGO for energy and environmental remediation. Fe3O4/SnO2/rGO is nearly 3 folds superior to Fe3O4/rGO and SnO2/rGO. High-capacitance of 967.5 F g−1 at a current density of 1 A g−1. Capacity retention of 98% over 5000 cycles. Easy-recoverable photocatalyst for multiple uses with more than 90% photocatalytic activity.