Sintesis Dan Karakterisasi Nanokomposit Fe₃O₄/Nitrogen-Doped Carbon Dots (N-CDs) Dengan Metode Sonikasi

Abstract

Nitrogen-Doped Carbon Dots (N-CDs), which are water-soluble, tend to be difficult to separate from the aqueous phase. To overcome this issue, Fe₃O₄ is used as a nanocomposite-forming material due to its magnetic properties, which enable separation from solution using an external magnetic field. Additionally, Fe₃O₄ possesses a high surface area and good biocompatibility. This study aims to synthesize and characterize Fe₃O₄/N-CDs nanocomposites using the sonication method. The synthesis process involved mixing Fe₃O₄ powder and N-CDs solution, sonicating for 30 minutes, allowing the mixture to settle, washing, drying at 90°C for 4 hours, and characterizing the product. UV-Vis analysis revealed two main absorption peaks at 350–380 nm, corresponding to n → π* transitions, and 650–700 nm, indicating absorption tails due to surface effects and interactions between N-CDs and Fe₃O₄ particles, with a band gap range of 2.18–2.20 eV. Photoluminescence analysis showed an emission peak at 520 nm. FTIR analysis confirmed the presence of functional groups such as –OH, –NH, C=O, C=C, C–N, and C–O, along with the Fe–O metal bond. XRD analysis showed characteristic peaks of the spinel structure of Fe₃O₄ with a crystallite size of approximately 15,75 nm, while the N-CDs signal was not detected due to their amorphous nature and low intensity. SEM imaging revealed an irregular and porous surface morphology with a particle size of around 72.8 nm. VSM analysis showed a saturation magnetization (Ms) of 54.26 emu/g, remanence (Mr) of 5.68 emu/g, and coercivity (Hc) of 113.30 Oe.