Facile synthesis of hierarchical NiO/NiFe₂O₄ microsphere composite as efficient visible photocatalyst for 2,4-DCP degradation

It is highly desired to develop efficient photocatalysts with recycling property for practical application to degrade toxic pollutants. Herein, nanosheet-assembled NiFe₂O₄ microspheres with commendable activity are successfully synthesized by a facile solvothermal reaction with NH₄F as the modifier, and their photoactivities are further improved by coupling with NiO through an in situ growth process. The optimized nickel oxide (NiO)/nickel ferrite (NiFe₂O₄) microsphere composite (5NiO/NFO-4) exhibits a satisfactory photocatalytic activity for 2,4-dichlorophenol (2,4-DCP) degradation under visible-light irradiation, which is attributed to its wide visible-light response, well-designed hierarchical structure and enhanced charge transfer and separation by coupling NiO as a high-level energy platform to accept electrons. Moreover, it is found that the NiO/NiFe₂O₄ microsphere photocatalysts can be easily collected and recycled owing to the distinctive magnetic properties. This work provides a feasible route to rational design visible-light-driven photocatalysts with high-activity for environmental remediation and purification with good recyclability.