Synthesis and characterization of bifuntional magnetic-optical Fe3O4@Hollow@ZnS core-shell microspheres

Bifunctional Fe3O4@ZnS microspheres with hollow heterostructures have been successfully fabricated by a simple hard-templating method. XRD, TEM, MPMS, and fluorescence spectrophotometer had been to investigate the as-prepared materials. The results showed that there is controllable hollow structure between Fe3O4 cores and ZnS layer. The Ms values of Fe3O4 and Fe3O4@Hollow@ZnS microspheres are 86.2 emu/g and 53.1 emu/g at 300 K, respectively. When excited by 353 nm low-power UV lamps, the composites have a broad blue light emission band between 440 and 500 nm. As the hard template, the amorphous SiO2 plays a key role in the forming process of the hollow structure. The presence of the hollow structures blocks the energy transfer between ZnS and Fe3O4 particles, which reduces the probability of fluorescence quenching. Furthermore, the hollow cavity size of the microspheres can be easily controlled by adjusting the thickness of SiO2 layer, which can affect the photocatalytic properties.