α-Fe₂O₃-rGO nanocomposites for environmental remediation: green synthesis, photocatalysis, and dye adsorption kinetics

A green and rapid microwave-assisted method was successfully developed for synthesizing α-Fe₂O₃ nanostructures and α-Fe₂O₃-rGO NCs using Urtica dioica L. extract as a natural reducing and stabilizing agent. As synthesized materials have been characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV–Visible spectroscopy, and scanning electron microscopy (SEM). The surface morphological analysis reveals that α-Fe₂O₃ exhibited distinctive octahedral-like morphologies. Leveraging the same phytochemical-based approach, α-Fe₂O₃-rGO nanocomposites (NCs) were also prepared, with morphologies uniformly anchored onto the surface of reduced graphene oxide (rGO) nanosheets, forming a well-dispersed hybrid system. The resulting materials demonstrated excellent performance in both photocatalytic degradation and adsorption of organic dyes such as Safranin, Malachite Green (MG), and Congo Red (CR). Under UV irradiation, the α-Fe₂O₃-rGO NCs achieved superior degradation efficiency (91.4 %) and removal efficiency (87 %) for Safranin within 30 min. Adsorption behavior followed pseudo-first-order kinetics, with isotherm fitting to both the Freundlich and Langmuir models and a maximum adsorption capacity of 235 mg/g. The nanocomposites maintained strong reusability over three cycles, confirming their stability. These findings highlight the (α-Fe₂O₃-rGO) NCs as promising candidates for sustainable wastewater treatment applications.