Electrochemical detection of dopamine using van der waals-interacted NiO–ZnO-functionalized reduced graphene oxide nanocomposite

The in situ Nickel oxide-zinc oxide-doped reduced graphene oxide (NiO–ZnO/rGO) nanocomposite is synthesized by the hydrothermal method. NiO–ZnO/rGO nanocomposite-modified glassy carbon electrode (GCE) utilized as electrochemical sensor for dopamine sensing. Scanning electron microscopy (SEM), RAMAN spectroscopy, Transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used for morphological and structural characterizations of NiO–ZnO/rGO nanocomposite. Further investigation of the redox response and the charge transfer characteristics of dopamine (DA) at NiO–ZnO/rGO-modified GCE tested using cyclic voltammetry and electrochemical impedance spectroscopy. The prepared GCE nanocomposite-modified electrochemical sensor show a linear response of redox peak current for DA in the concentration range of 0.0041–0.054 µM. The active electrochemical surface area of the sensor found to be 2.1 × 10 −6 cm 2 , with low detection limit of 0.0076 µM and high sensitivity of 12.19 µA L cm −2 Mol −1 . The constructed sensor has close to 100% recovery toward DA in voluntarily collected human urine samples. The composite exhibits good reproducibility for sensing DA for month, which is an indication of their repeatability. Also designed sensors show 123% retention current to 100 cycles of CV indicates the good stability of the sensor to DA, which are crucial for the fabrication of further devices.