An efficient and eco-friendly ultraviolet (UV) irradiation method was developed to synthesize a ternary nanocomposites of gold-polyindole-reduced graphene oxide (Au-PIn-RGO), and as-prepared nanomaterial was then used to fabricate an electrochemical caffeine (CAF) sensor. In the synthesis process, the polymerization of the indole monomer, the reduction of Au3+ ions and GO occurred simultaneously by UV irradiation without using any chemical reagents. The synthesis procedure was simple, inexpensive and green environmentally. Morphology, structure and composition of the Au-PIn-RGO nanocomposites were characterized by various technologies including UV-visible (UV-Vis) spectroscopy, fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Under the optimum conditions, a linear relationship existed between oxidation peak currents and the concentration of CAF in the range of 0.8–40 μM and 40–1000 μM, with a detection limit of 0.26 μM (S/N = 3). The proposed method was successfully applied to determine the CAF in beverages.
Published in: "Journal of the Electrochemical Society".