Synthesis of Fe₃O₄-NH₂-APTES@rGO@SiO₂ core–shell magnetic microspheres for efficient aqueous phenol photocatalytic degradation

This study aims to synthesize a ternary Fe₃O₄-NH₂-APTES@rGO@SiO₂ core–shell magnetic microspheres by modified Stöber technique to photodegrade aqueous phenol under UV-C light effectively. Results of the X-ray diffractogram of the as-synthesized Fe₃O₄-NH₂-APTES@rGO@SiO₂ core–shell magnetic microspheres showed the nanoparticles having an average size of 126.00 nm, comparable to 150.00 nm seen in the FESEM micrograph. These sizes were supported by the EDX and FTIR results which verified the presence of Fe₃O₄, rGO, and SiO₂, and the TEM micrograph revealed them to be spherically shaped. Also, the thermally more stable microspheres than the pure individual components and binary nanocomposites were evident in their corresponding TGA thermograms.Similarly, the photoluminescence spectra of the Fe₃O₄-NH₂-APTES@rGO@SiO₂ microspheres supported their higher photodegrading ability as a consequence of an extended e^-/h⁺ recombination rate. The microspheres were more effective in photo-catalytically degrading the highest amount of aqueous phenol (∼89 %) than Fe₃O₄-NH₂-APTES@rGO (∼74 %), Fe₃O₄-NH₂-APTES@SiO₂ (∼78 %), and pure Fe₃O₄ (∼62 %), under an optimized condition of 0.2 g/350 mL catalyst loading and 50 ppm of initial phenol concentration. The enhanced photoactivity was ascribed to the high stability and specific surface of SiO₂, the synergistic influence of Fe₃O₄, and the rGO sheet's rapid electron transport·H₂O₂ enhanced phenol degradation to 94 %.