Fabrication of Fe ₃ O ₄ /GO-based precious metal composite and research in comprehensive photocatalysis of organic pollutants with mechanism

As a common antibacterial drug and organic dye, ciprofloxacin (CIP) and acid orange (AO) residues have posed a serious threat to ecosystems and human health. To solve this problem, Fe 3 O 4 /GO-based precious metal composites (Fe 3 O 4 /GO/M: Fe 3 O 4 /GO/Au, Fe 3 O 4 /GO/Ag) were prepared as catalysts to photocatalyze pollutants. The Fe 3 O 4 /GO/Au and Fe 3 O 4 /GO/Ag) composites underwent comprehensive characterization, including X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS)- mapping, and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and diffuse reflectance spectroscopy (DRS) were carried out. It was demonstrated that the Fe 3 O 4 /GO/M composite were successfully fabricated with excellent properties. The Fe 3 O 4 /GO and Fe 3 O 4 /GO/M composite performed adsorption and unique photocatalysis properties, respectively. The Fe 3 O 4 /GO/M composites were assessed through synergized adsorption-photocatalysis degradation of AO II and CIP. The pseudo-first-order and pseudo-second-order kinetic models, as well as Langmuir and Freundlich isotherms models were employed to evaluate the adsorption performance. The influence of various factors on photocatalysis were investigated in detail. The findings indicated that the composites demonstrated remarkable capabilities for pollutant removal, with the degradation rates of (84 ± 3.3) % for AO II by Fe 3 O 4 /GO/Au and (89 ± 3.9) % for CIP by Fe 3 O 4 /GO/Ag, respectively. The scavenger analysis and total organic carbon (TOC) was also conducted. The photocatalysis mechanisms was also highlighted in detail. It was primarily attributed to the surface plasmon resonance (SPR) of the precious metals and the charge transfer of graphene oxide (GO). Furthermore, the catalyst exhibited nice reusability in six consecutive cycle experiments. A preferable approach to fabrication of Fe 3 O 4 /GO/M composite and photocatalytic degradation of organic pollutants was established.