An electrochemical sensor based on reduced graphene oxide decorated with polypyrrole nanofibers and zinc oxide–copper oxide p–n junction heterostructures for the simultaneous voltammetric determination of ascorbic acid, dopamine, paracetamol, and tryptophan

Abstract

A three-dimensional porous nanocomposite of reduced graphene oxide decorated with polypyrrole nanofibers and zinc oxide–copper oxide p–n junction heterostructures (3DCu_xO–ZnO NPs/PPy/RGO) was fabricated and used for the simultaneous voltammetric determination of ascorbic acid (AA), dopamine (DA), paracetamol (PAR), and tryptophan (TRP). The morphology and structure of the nanocomposite were characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Measurements were carried out by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. An optimized 3DCu_xO–ZnO NPs/PPy/RGO/GCE modified electrode had a large surface area and displayed high selectivity, with linear responses from 0.08 to 475 μM, 0.04 to 420 μM, 0.033 to 400 μM, and 0.053 to 480 μM and detection limits of 0.024 μM, 0.012 μM, 0.010 μM, and 0.016 μM (S/N = 3) for AA, DA, PAR, and TRP respectively. In addition, the analytical application of the proposed sensor was successfully achieved for the determination of these species in real human blood serum samples.