Facile synthesis of magnetic-fluorescent iron oxide-geothermal silica core/shell nanocomposites via modified sol–gel method

This study successfully synthesizes magnetic fluorescent iron oxide silica core/shell nanocomposites (MFSNC) derived from natural geothermal silica. The nanostructures comprise an iron-oxide core and a fluorescent mesoporous silica outer layer. X-ray diffraction (XRD) analysis indicated diffraction peaks of amorphous silica with crystallites of magnetite types in the MFSNC samples. Transmission electron microscopy combined with energy-disperse X-ray spectroscopy were used to observe the morphological structure, which showed nanoparticles of MFSNC with Fe, Si, O, and N elements. Among varying ratios of ferric salts, the MFSNP0.5 sample exhibited the highest fluorescence intensity (280.5073 a.u.). It demonstrated superior fluorescence stability in water (pH = 7) compared to other samples, as investigated by fluorescence spectrophotometer. Additionally, this sample displayed ferromagnetic properties, with a magnetic saturation (MS) of 14.57 emu/g and a loop area value of 0.7 kOe.emu/g, determined by the vibrating sample magnetometry. This work details the successful synthesis of MFSNC nanocomposites with tailored magnetic and fluorescent properties. Notably, the MFSNC0.5 sample stands out for its superior fluorescence intensity, stability in water, and desirable ferromagnetic characteristics.