Highly Sensitive Detection of Dopamine at Ionic Liquid Functionalized RGO/ZIF-8 Nanocomposite-Modified Electrode

A hybrid and hierarchical nanocomposite was successfully prepared by the growth of zeolitic imidazolate framework-8 (ZIF-8) on the template of ionic liquid (IL, [Bmim][BF4]) functionalized reduced graphene oxide (IL-RGO). The structure and morphology of the IL-RGO/ZIF-8 nanocomposite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrometer (FTIR), and Raman spectroscopy. The results showed that RGO sheets were refrained from restacking by IL, and ZIF-8 nanoparticles grew well on the surface of IL-RGO. Owing to the synergistic effect from large surface area and excellent electrocatalytic activity of ZIF-8 and great electrical conductivity of IL-RGO, a highly sensitive sensor for dopamine (DA) can be obtained. IL-RGO/ZIF-8-modified electrode exhibits good electrocatalytic activity and electroconductive properties towards DA which were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Compared with bare or IL-RGO-modified electrodes, the IL-RGO/ZIF-8-modified electrode effectively depressed the oxidation overpotential of DA. The linear response range of DA was from 1.0x10-7 to 1.0x10-4 mol/L with a low detection of limit 3.5x10-8 mol/L. In addition, the sensor was shown to provide satisfactory stability for the determination of DA.