Multifunctional magnetic Fe3O4/GO/Ag composite microspheres for SERS detection and catalytic degradation of methylene blue and ciprofloxacin

It is greatly significant to remove organic dyes and antibiotics in water because they are extremely harmful for human health and environment. In this work, we successfully developed magnetic Fe3O4/GO/Ag composite microspheres, using Fe3O4 microspheres as cores to wrap graphene oxide (GO) interlayer and further in situ depositing silver nanoparticles onto GO layer. The microspheres were characterized by SEM, XRD, XPS and Raman spectroscopy. As compared to Fe3O4/Ag microspheres, Fe3O4/GO/Ag composite microspheres displayed higher activity for SERS detection, and also catalytic reaction due to the synergistic interaction of GO nanosheets and Ag nanoparticles. Subsequently, the Fe3O4/GO/Ag composite microspheres were employed to quantitatively detect aromatic molecules, methylene blue (MB) in aqueous solution, showing the limit of detection was low down to 10−9 M and the correlation coefficients (R2) of the linear relationship between SERS intensities and logarithmic concentrations was high up to 0.91. Moreover, the Fe3O4/GO/Ag composite microspheres as catalysts completely degraded methylene blue and ciprofloxacin in 12 min with the presence of NaBH4. Finally, Fe3O4/GO/Ag composite microspheres were utilized to effectively follow the degradation reaction process of MB by SERS. Taken together, Fe3O4/GO/Ag composite microspheres present SERS application potentials in terms of trace and quantitative detection of chemicals, and in-situ monitoring catalytic degradation of organic pollutants.