Application of Nitrogen-Doped Reduced Graphene Oxide-Persimmon Tannin Nanocomposites for Electrochemical Detection of Cd (II) in Water Resources

Abstract

An ultrasensitive electrochemical biosensor for the detection of Cadmium (Cd(II)) was successfully constructed based on nitrogen-doped reduced graphene oxide-persimmon tannin (PT-N-RGO) nanocomposite and gold nanoparticles (Au NPs) modified screen-printed electrode (SPE). The structure and morphology of the prepared PT-N-RGO nanocomposite were characterized by ultraviolet-visible spectroscopy (UV–vis), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Each step for the electrochemical biosensor was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Au NPs, as modified electrode material, not only increased the effective surface area of the electrode, but also promoted the electron transfer during the redox reaction. The PT-N-RGO further increased the electron transfer rate, thereby improving the conductivity of the electrode and providing more binding sites for the subsequent capture of Cd (II). The biosensor showed good selectivity, stability and reproducibility for the determination of Cd (II). Also, the biosensor was applied to the analysis of real water samples and satisfactory results were obtained, which were verified by inductively coupled plasma mass spectrometry (ICP-MS). This study provided a new idea for the effective determination of trace heavy metals in the environment.