A sensitive electrochemical sensor based on Fe₃O₄ magnetic nanoparticles/chitosan/graphene composite for detection of Pb²⁺ in aqueous solutions

We propose here a fabrication of an electrochemical sensor to detect heavy metal ions based on a glass carbon electrode (GCE) modified with a composite system consisting of graphene, chitosan, and Fe₃O₄ nanoparticles (GrCF) by using square wave voltammetry (SWV) measurements. The GrCF composite was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and Raman spectroscopy. GrCF consists of thin and smooth sheets stacked in overlapping layers to form porous structures. In the GrCF composite, graphene acts as a substrate with a high electrochemical activity and a good electrical conductivity, Fe₃O₄ nanoparticles are uniformly distributed on the graphene thanks to chitosan as a binder, the functional groups of chitosan (− OH, − NH₂) have the ability to form complexes with heavy metal ions, and the excellent adsorption capacity of Fe₃O₄ nanoparticles has enhanced the electrochemical reactions. The GrCF/GCE can detect Pb²⁺ ions with a linear range from 4 to 16 μM, a low detection limit of 3.57 μM, and a sensitivity of 8.623 μA μM⁻¹. Furthermore, the repeatability of the measurements are reliable with a standard deviation (SD) of 0.15 μA and a relative standard deviation (RSD%) of 4.16%. Additionally, Pb²⁺ was detected in the real sample at potentials of − 0.50 V/ − 0.52 V with calculated recovery values for two measurements of 89.02% and 89.43%. The electrode modification method based on the GrCF composite promises outstanding advantages in the field of electrochemical sensors for detection of heavy metal ions.