Ultrahigh Dispersion of Fe3O4 NPs on Cellulose Nanofibers: Unlocking Superior Visible-Light Photocatalysis.

Constructing cost-effective and efficient photocatalysts is crucial for removing harmful contaminants from water sources, ensuring a greener and healthier environment. In this study, highly dispersed magnetic iron oxide (Fe3O4) nanoparticles (NPs) were successfully decorated on cellulose nanofibers (CNFs) by using a simple interfacial strategy. Four hybrid materials (Fe3O4-CNF1, Fe3O4-CNF2, Fe3O4-CNF3, and Fe3O4-CNF4) were systematically synthesized, with Fe3O4-CNF4 identified as the most efficient photocatalyst. The optimized Fe3O4-CNF4 hybrid exhibited a high surface area (54.12 m2/g), enhanced light utilization, and improved charge separation, leading to superior photocatalytic performance. It achieved a 95% removal rate of Rhodamine B (RhB) in 120 min and 99% removal rate of Methylene Blue (MB) in 150 min when exposed to visible irradiation. Moreover, Fe3O4-CNF4 demonstrated excellent recyclability, maintaining high efficiency over five reuse cycles with only ∼7% activity loss. Stability tests under varying catalyst concentrations and pH conditions further confirmed its robustness. Additionally, the primary active species, potential degradation pathways of MB, and the underlying reaction mechanism were systematically analyzed. These findings highlight Fe3O4-CNF4 as a promising visible-light-responsive and reusable photocatalyst for wastewater treatment.