Tuning magnetic and luminescent properties of iron oxide@C nanoparticles from hydrothermal synthesis: Influence of precursor reagents

Magneto-luminescent nanocomposites were obtained by coating coprecipitated iron oxide nanoparticles with a functionalized carbon layer by hydrothermal treatment, using different organic precursors (D-glucose and p-phenylenediamine). The nanomaterials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), RAMAN, infrared (FTIR), UV-vis and photoluminescence (PL) spectroscopic analysis, vibrating sample magnetometry (VSM) and zetametry. Remarkable contrasting changes in the structural and magnetic properties of nanocomposites were identified after the carbon coating, which was directly related to the pre-cursor used. Crystalline phase transformations were observed with a decrease in the saturation magnetization (-80%) using p-phenylenediamine and an increase (+22%) using glucose, relative to uncoated magnetic core. The distinct photoluminescent properties with multicolored emissions on long-wavelength are ascribed to the carbon shell and to the chemical moieties, such as amino, carbonyl, carboxylate, and hydroxyl groups on the surface. This makes it possible for different surface states to be responsible for emission, and these chemical groups are also responsible for a higher colloidal stability of nanocomposites in alkaline medium. The tunability of the properties of nanocomposites from the conditions of synthesis opens a wide range of applications for these nanomaterials, such as ion detection, magnetohyperthermia, and theranostics.