Charge-Carrier Separation and Dynamic Alteration by Utilizing External Magnetic Field in rGO/γ-Fe₂O₃ Heterostructure for Improved Photodegradation of Organic Pollutants

This study introduces an innovative method to improve photocatalytic degradation using the presence of an external magnetic field. Magnetically active γ-Fe 2 O 3 nanoparticles were synthesized using a sustainable method by recycling waste toner powder, thereby offering an eco-friendly route to valorize hazardous e-waste. To engineer a highly effective photocatalyst, these nanoparticles were additionally decorated with reduced graphene oxide (rGO) sheets. Comprehensive characterization techniques were employed to analyze the optical, electronic, and physiochemical properties of the synthesized photocatalyst. Integrating rGO enhances the overall conductivity and specific surface area of the nanocomposite, thereby increasing the number of active sites for pollutant degradation. In addition to improving charge separation, the addition of rGO decreased the band gap from 2.3 eV (γ-Fe 2 O 3 ) to 1.39 eV (rGO/γ-Fe 2 O 3 ), increasing the material’s efficiency in visible light. The rGO/γ-Fe 2 O 3 based photocatalyst displays impressive efficacy by degrading 99.8% of 10 mg/L aqueous solution of RhB by mere utilization of 0.3 mg/mL dosage. A mixture of diverse category of pollutants with a cumulative concentration of 30 mg/L was effectively broken down in a brief amount of time to replicate real-world conditions. Interestingly, the photodegradation efficiency was further improved by the application of an external magnetic field with an intensity of 0.25 mT, which lowers the degradation time from 60 to 40 min for 30 mg/L aqueous solution of RhB pollutant. By converting e-waste into useful photocatalysts, this work offers a sustainable option for managing e-waste in addition to showcasing a potential method for efficient pollutant removal.