Magnetically recoverable ZnO/NiFe2O4 heterostructures for photocatalytic degradation of dye and antibiotic pollutants

ZnO/NiFe 2 O 4 heterostructured photocatalysts were synthesized via a hydrothermal route followed by thermal treatment for efficient pollutant degradation and magnetic recovery. Pristine NiFe 2 O 4 was first optimized, with the sample prepared at 180 °C showing the best crystallinity and magnetic response. Using this ferrite precursor, ZnO/NiFe 2 O 4 composites with different NiFe 2 O 4 loadings were fabricated. Structural and morphological analyses suggested the coexistence of wurtzite ZnO and spinel NiFe 2 O 4 , with well-distributed ferrite particles on ZnO nanorods, forming effective heterointerfaces. NiFe 2 O 4 incorporation enhanced visible-light absorption and imparted magnetic behavior to the composites. Among the samples, ZnO@NFO-1 containing 6 wt% NiFe 2 O 4 exhibited the highest photocatalytic activity, achieving 97.3% RhB degradation under Xenon irradiation and approximately 98% degradation of RhB and CIP under UV irradiation, together with good reusability. Radical-trapping experiments demonstrated pollutant-dependent degradation mechanisms, in which h + was identified as the dominant reactive species for CIP degradation, with •OH contributing as a secondary oxidation pathway, whereas •OH predominantly governed RhB degradation, accompanied by a secondary contribution from h + . The superior performance of ZnO@NFO-1 is attributed to the optimal balance between enhanced light harvesting, efficient charge separation, heterojunction formation, and preservation of ZnO active sites. These findings highlight ZnO/NiFe 2 O 4 composites as promising magnetically recoverable photocatalysts for wastewater treatment.