Synthesis, characterization, and luminescence properties of BiVO4:Eu3+ embedded Fe3O4@mSiO2 nanoparticles

Highlights: • CaF₂ resulted in the improved uniformity and magnetic response for Fe₃O₄ nanospheres. • Fe₃O₄@mSiO₂ with tunable pore size were achieved by using a double-template micelle system. • Fe₃O₄@mSiO₂/BiVO₄:Eu³⁺ nanoparticles were prepared with a modified Pechini sol-gel process. • The addition of 2-thenoyltrifluoroaceate (TTA) further enhanced the fluorescence. -- Abstract: Magnetic Fe₃O₄ nanospheres with high dispersion, high saturation magnetization and narrow particle size distribution were synthesized by a CaF₂ mediated solvothermal method. Next, a nonporous silica layer and a mesoporous silica (mSiO₂) layer were uniformly coated on the surface of the magnetic nanospheres sequentially to form Fe₃O₄@mSiO₂ nanoparticles. It was shown that the pore size and thickness of the mSiO₂ shell could be fine-tuned by adjusting the composition of the double-template micelle system consisting of a partially fluorinated short-chain anionic fluorocarbon surfactant and cetyltrimethylammonium bromide. Finally, Eu³⁺ in the BiVO₄ host was embedded on the surface of Fe₃O₄@mSiO₂ nanoparticles with the Pechini sol-gel process, thus to form magnetic fluorescent nanoparticles. It was found that the fluorescence of the inorganic nanoparticles can be further enhanced by the complexation of 2-thenoyltrifluoroaceate (TTA) to the Eu³⁺ on the surface of the nanoparticles. The as-prepared nanoparticles were well characterized and the preparation process was optimized in order to establish a robust preparation method for the multiple functionalized luminescent nanoparticles.