Petal-like graphene-Ag composites with highly exposed active edge sites were designed and constructed for electrochemical determination of metronidazole

Petal-like graphene-Ag (p-GR-Ag) composites with highly exposed active edge sites were designed and constructed in this work. Petal-like graphene (p-GR) was prepared using a HCl assisted hydrothermal method, which was made of basal planes and highly reactive edge planes to provide more active sites. Then the p-GR can be intentionally utilized as nucleation sites for subsequent Ag nanoparticles (NPs) deposition via modified silver mirror reaction. The composites were characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. The combination of zero-dimensional (0D) Ag NPs on a two-dimensional (2D) graphene (GR) support that came into being three-dimensional (3D) structure created a sensor for electrochemical detection of metronidazole. The designed sensor exhibited well bimodal linear behaviour in the metronidazole concentration range between 0.05 to 10 μM and 10 to 4500 μM with a detection limit of 28 nM (S/N = 3). The mechanism and the heterogeneous electron transfer kinetics constant of the metronidazole reduction were discussed in the light of the rotating disk electrode (RDE) experiments. Moreover, validation of the applicability of the prepared sensor was carried out by detecting metronidazole in human urine and local lake water samples.