Preparation of magnetic recoverable nanosize Cu-Fe₂O ₃/Fe photocatalysts

Iron based catalysts generally have the advantage of the easily operated magnetically recovery from application sites. In the present work, paramagnetic iron and copper core-shell nanoparticles having the iron fractions (X _Fe = Fe/(Cu+Fe)) of 0.33-1.0 were prepared and characterized by in situ synchrotron X-ray absorption and scattering spectroscopy. During the temperature-programmed carbonization (TPC) of Cu²⁺- and Fe ³⁺-β-cyclodextrin (CD) complexes, a rapid reduction of Cu(II) occurs at about 453 K together with a growth of the metallic copper (Cu). Iron proceeds in the distinct growth path. At 453-513 K, the Fe(III) → Fe(II) → Fe consecutive reduction is observed. The unreduced Fe(III) (7-13%) is coated on the surfaces of the Fe nanoparticles (as Fe₂O ₃/Fe). Growth of the Fe nanoparticle is inhibited by the surface Fe₂O₃, while the steady growth in Cu is observed. The Cu has a size range of 14-18 nm in diameter, compared to the small Fe ₂O₃/Fe ones (3-6 nm). Under the UV-visible light irradiation for four hours, methylene blue can be photocatalytically degraded (>90%) by the (Cu-Fe₂O₃/Fe)@C. The (Cu-Fe ₂O₃/Fe)@C photocatalysts can effectively oxidize dye molecules, providing a promising alternative for dye degradation using solar energy. Recovery of the (Cu-Fe₂O₃/Fe)@C photocatalysts can be attained by applying external magnetic field to trap the ferromagnetic Cu-Fe₂O₃/Fe nanoparticles, which suggests an economically attractive process, especially applied in photocatalytic degradation of dye-contaminated wastewater.