Ligand‐Induced Evolution of Intrinsic Fluorescence and Catalytic Activity from Cobalt Ferrite Nanoparticles

To develop CoFe₂O₄ as magneto‐fluorescent nanoparticles (NPs) for biomedical applications, it would be advantageous to identify any intrinsic fluorescence of this important magnetic material by simply adjusting the surface chemistry of the NPs themselves. Herein, we demonstrate that intrinsic multicolor fluorescence, covering the whole visible region, can be induced by facile functionalization of CoFe₂O₄ NPs with Na‐tartrate. Moreover, the functionalized CoFe₂O₄ NPs also show unprecedented catalytic efficiency in the degradation of both biologically and environmentally harmful dyes, pioneering the potential application of these NPs in therapeutics and wastewater treatment. Detailed investigation through various spectroscopic tools unveils the story behind the emergence of this unique optical property of CoFe₂O₄ NPs upon functionalization with tartrate ligands. We believe our developed multifunctional CoFe₂O₄ NPs hold great promise for advanced biomedical and technological applications.