Green Synthesis of Fe_3O_4@CDs Nanocomposites and its Performance on Optical and Magnetic Properties

D was synthesized from dried banana leaves using a simple heating method. Then, the Fe_3O_4@CDs nanocomposite was synthesized using the hydrothermal method of one-pot and two-pot synthesis. The CD is transparent under visible light and looks blue and green under UV illumination. The photoluminescence properties of CDs and Fe_3O_4@CDs nanocomposite were characterized using photoluminescence (PL) spectrophotometers. Fe_3_O4@CD synthesized using a one-pot technique has an emission band that broadens towards longer wavelengths, or "redshift." In contrast, Fe3O4@CDs synthesized using a two-pot technique has a higher luminescent intensity than pure CDs. A transmission electron microscopy (TEM) image shows the core-shell structure of the Fe_3O_4@CDs nanocomposite. Vibrating sample magnetometry (VSM) results show that the nanocomposite has a saturation magnetization of 22.3 emu/g and a coercivity field of 85.41 Oe. The functional groups in Fe3_O_4@CDs nanocomposite are Fe-O bonds, indicating the formation of Fe_3O_4, whereas O-H and C=O bonds indicate the formation of CDs. Based on the optical and magnetic characterization, it can be concluded that this material can be developed for a biomedical application, such as a bioimaging material.