Synthesis of Fe3O4/CdSe/CdS magnetic fluorescent nanocomposites by a stepwise heterocoagulation approach

Abstract In this thesis, Fe 3 O 4 /CdSe/CdS magnetic fluorescent nanocomposites (MFNC) were synthesized by an approach of stepwise heterocoagulation. Fe 3 O 4 magnetic nanoparticles were prepared by hydro-thermal coprecipitation of ferric and ferrous ions. The as-prepared nanoparticles were modified by oleic acid, and then formed the anionic water based ferrofluids (FFs) by utilizing a nonionic surfactant of polyoxyethylene nonylphenol to create a colloidal suspension. CdSe/CdS quantum dots (QDs) were synthesized using mercaptoacetic acid as stabilizer. At last, Fe 3 O 4 /CdSe/CdS magnetic/luminescent bifunctional nanocomposites were prepared successfully using cationic polyethyleneimine (PEI) as a crosslinker. The as-synthesized nanocomposites possessed structure with an average diameter of 70–80 nm. They retained the strong photoluminescence effect of CdSe/CdS QDs and also exhibited a typical superparamagnetic behavior of Fe 3 O 4 nanoparticles.