Investigation of co-doped magnetite (Fe3O4) nanomaterials with reduced graphene oxide and bismuth for photocatalytic, supercapacitor, and antimicrobial applications

The present study reports the successful preparation of pure magnetite Fe₃O₄ (F), bismuth doped Fe₃O₄ (FB), reduced graphene oxide doped Fe₃O₄ (FR), and bismuth-rGO co doped Fe₃O₄ (FBR) using the simple co-precipitation process. The produced samples were subjected to morphological, optical, FTIR, and structural analyses. XPS- Photo electron spectroscopy indicates the presence of relevant elements and oxidation states. BET surface analysis shows the presence of enhanced surface area in conjointly doped Fe₃O₄ (FBR) and rGO doped Fe₃O₄ (FR). The photocatalytic activity of the materials (F, FB, FR, and FBR) against several organic dyes [MB, Rho-b, and Congo red (CR)] was investigated. Using the disc diffusion method, the antibacterial activity of the samples was investigated against a variety of gramme positive and gramme negative bacteria. The findings indicate that the co-doped magnetite nano composite exhibits strong antimicrobial activity. The synthesised materials were also used as electrode materials for supercapacitors. The electrochemical performance of the FBR-based supercapacitor was reliable, and it exhibited a high specific capacitance of 732.51 Fg^-1 at a current density of 1 Ag^-1. From the CV analysis, the measured capacitance was 440.67 Fg^-1 for a three-electrode configuration. The symmetric device has been constructed using bismuth and rGO co doped (FBR) nano composite and it exhibited a specific capacitance of 173 Fg^-1, specific energy of 24 W h Kg¹, and specific power of 1999 W Kg^-1 at a current density of 1 Ag^-1 with notable cyclic stability of about 89% and had average capacity retention and excellent coulombic efficiency which is about 95% up to 8000 cycles which is retained even after 18,000 cycles.