<scp>PVP</scp> ‐Coated Fe ₃ O ₄ /Fe ₂ O ₃ Nanocomposites for Efficient Photocatalytic Degradation of Organic and Inorganic Pollutants

ABSTRACT In this study, Fe 3 O 4 /Fe 2 O 3 and polyvinylpyrrolidone (PVP)‐capped Fe 3 O 4 /Fe 2 O 3 @PVP nanocomposites were synthesized via a controlled hydrothermal route and evaluated as multifunctional photocatalysts for the degradation of inorganic and organic pollutants. Structural analyses confirmed the coexistence of magnetite and hematite phases, with PVP incorporation inducing compressive lattice strain, reducing crystallite size from 19.91 to 14.83 nm, and increasing the specific surface area from 55.84 to 68.8 m 2 g −1 . UV–Vis spectroscopy revealed a slight red shift in the optical bandgap (from 1.25 to 1.04 eV), attributed to enhanced polymer–oxide electronic coupling. Morphological studies showed that PVP effectively minimized nanoparticle agglomeration, leading to improved dispersion and surface accessibility. Photocatalytic evaluations under UV irradiation demonstrated nearly complete degradation (~99.9%) of Cr(III) within 105 min and of the organic pollutants 2,4‐dinitroaniline and p‐bromohydroxybenzene within 120 min. The PVP‐capped Fe 3 O 4 /Fe 2 O 3 @PVP nanocomposite exhibited slightly superior efficiency and stability compared to the uncoated sample, owing to enhanced charge carrier separation, reduced electron–hole recombination, and improved interfacial contact with the pollutants. These findings highlight the potential of Fe 3 O 4 /Fe 2 O 3 @PVP nanocomposites as efficient, recyclable, and sustainable photocatalysts for water purification and environmental remediation.