Encapsulation of e‐Waste‐Derived Fe ₃ O ₄ Nanoparticles on Reduced Graphene Oxide Sheets: Harnessing Built‐In Potential for the Photodegradation of Diverse Pollutants

This research work demonstrates the engineering of rGO/Fe₃O₄ based heterojunction as cost-effective, highly efficient, and robust photocatalyst with readily recoverable and reusable characteristics. Herein, the Fe₃O₄ nanoparticles have been synthesized from the waste toner powder collected from used cartridges for advancing a magnetically separable photocatalyst. The Fe₃O₄ nanoparticles have been decorated on rGO sheets for enhancing the conductivity and retarding the recombination rate of photogenerated electron-hole pairs, as reflected by the decrease in photoluminescence intensity for rGO/Fe₃O₄ relative to pure rGO and Fe₃O₄. Additionally, the specific surface area has also improved from 12.93 m² g^-1 for Fe₃O₄ to 115.58 m² g^-1 in the case of rGO/Fe₃O₄. Henceforth, the rGO/Fe₃O₄ nanocomposite showcases remarkable performance for the removal of various pollutants like, rhodamine B (RhB) (98.5%), methylene orange (93.8%), methylene blue (99.99%), and tetracycline hydrochloride (95.4%) after 30, 40, 20, and 40 min of simulated solar light exposure, respectively, by utilizing 0.2 mg ml^- ¹ of photocatalyst. Furthermore, it degrades 74.3% of RhB pollutant with very high concentration of 30 mg L^-1 within 80 min of light irradiation. Additionally, this work also manifests the impact of different parameters, like dosage of photocatalyst and initial concentration of the pollutants and mixing of diverse pollutants on the photodegradation efficiency of nanocomposite. The scavenger's study is performed to investigate the active species involved in the photodegradation process. Furthermore, the role of built-in potential at the interface of heterojunction is thoroughly discussed to understand the mechanistic intricacies of the charge transfer process during the photodegradation process.