Tailoring Photocatalytic Properties of Magnetically Separable Magnetite–Graphene Hybrid Materials for Efficient Dye Degradation

Magnetite-based hybrid materials have attracted considerable attention for environmental remediation, owing to the dual benefits of iron oxide nanoparticles, including intrinsic photocatalytic activity and magnetic separability. However, issues such as nanoparticle aggregation and limited tunability of nanocomposite properties remain challenges. In this study, we report a facile method for synthesizing magnetically separable magnetite–graphene hybrid materials with tailorable photocatalytic properties toward efficient treatment of methylene blue pollutant in water. The magnetite–graphene hybrid materials have been synthesized via plasma electrochemical exfoliation of a graphite electrode in a mixture of 0.5 M KOH and 5% (NH₄)₂SO₄ with controlled Fe³⁺/Fe²⁺ concentration ratios. The as-synthesized magnetite–graphene have been characterized by scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, Fourier-transform infrared spectroscopy, UV-Visible diffuse reflectance spectroscopy, nitrogen adsorption/desorption isotherms, electrochemical impedance spectroscopy, and vibrating sample magnetometry. Through an experimental optimization process, the optimized magnetite–graphene exhibits a smaller band gap, lower electrical impedance, superior specific surface area, and comparable superparamagnetic properties, signifying a greater treatment efficiency of the dye pollutant. As expected, it demonstrates a high photocatalytic degradation of methylene blue (efficiency of 97.2%), representing a 1.5-fold increase, along with a high reusability (approximately 95% retention of degradation efficiency). This study therefore suggests a high potential for advancing the practical uses of magnetite–graphene hybrid materials in various technological and environmental aspects, particularly emphasizing their effectiveness in treating organic pollutants in water.