Nanosheet-based 3D hierarchical ZnO structure decorated with Au nanoparticles for enhanced electrochemical detection of dopamine

A biocompatible Au-ZnO nanocomposite was used to fabricate a sensitive sensor for the detection of dopamine (DA). High-density Au nanoparticles (AuNPs) were homogeneously loaded onto a nanosheet-based three-dimensionally (3D) hierarchical ZnO matrix. The high specific surface area of the nanosheet-based three-dimensionally (3D) hierarchical ZnO favored the high density loading of AuNPs, which helped efficiently catalyze the oxidation of DA. The Au-ZnO nanocomposite was characterized by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and electrochemical impedance spectroscopy (EIS). The electrocatalytic activity toward the oxidation of dopamine was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The sensors exhibited sensitive responses to DA with a linear range of 0.1-300 μM and a detection limit of 0.02 μM based on S/N = 3. The good analytical performance and long-term stability of the proposed sensor can be attributed to the synergistic effect of the nanosheet-based ZnO structure and gold nanoparticles on the electrochemical oxidation of dopamine.