AuNPs-Ultrathin/Graphitic-C3N4 Nanosheets As a Sensitive Platform for Electrochemical Detection and Determination of Dopamine

The present work describes developing a selective and sensitive electrochemical sensor using the AuNPs/ Graphitic-C3N4 (ug-C3N4) nanocomposites for the voltammetric detection of dopamine. This nanocomposite is obtained by loading gold nanoparticles (AuNPs) onto an ultrathin nano -sheet of graphitic carbon nitride (utgC3N4). Firstly, the bulk g-C3N4 was produced through a thermal poly-condensation process, and then, the ugC3N4 nanosheets were obtained by exfoliating the bulk g-C3N4. The nanocomposite of graphitic carbon nitride decorated with AuNPs exhibits highly sensitive electrochemical signals, suggesting successful immobilization of AuNPs/ug-C3N4 onto the electrode surface. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) are used for the structural and morphological characterization of the AuNPs/utg-C3N4 composite. Differential pulse and cyclic voltammetric methods are used for the application of AuNPs/utg-C3N4 modified electrodes as an electrochemical sensor for the detection of dopamine (DA). The prepared electrode shows two wide linear ranges from 5.00 - 99 nM and 99---476 nM, with a detection limit of 0.24 nM (S/N = 3) in voltammetric detection of DA. Using the standard addition method, the electrochemical sensor based on AuNPs/utg-C3N4 nanocomposite is successfully applied for detecting and quantifying DA in human urine samples.