Enhancing mercury (II) ion detection with graphene oxide-cerium oxide nanocomposites: Enzyme free ultrasensitive detection

This study discusses how gold (Au) electrodes were modified by immobilizing graphene oxide-cerium oxide (GO-CeO2) nanocomposite to detect mercury (II) (Hg2+) ions selectively. The GO-CeO2 nanocomposite was prepared using the sonochemical method after synthesis of GO through a modifier Hummers' method and CeO2 via a coprecipitation technique. The structural, morphological, and optical characteristics of the nanocomposite were assessed using X-ray diffraction (XRD), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS), respectively. Cyclic voltammetry (CV) provided the selective electrochemical response for Hg2+ among different divalent metallic ions. Scan rates (ranging from 5 to 300 mV/s) confirmed the stability of the modified electrode. It was suggested that the Hg2+ ion and modified Au electrode interacted through both diffusion-controlled and surface-controlled mechanisms, with diffusion-controlled interaction being the dominant one. Differential pulse voltammetry (DPV) was chosen to assess sensitivity by conducting concentration profiles in the range of 10 fM to 1 mM. The calculation yielded a limit of detection of 1.87 fM (fM). The developed sensor represents a promising platform for the ultrasensitive detection of Hg2+ ions.